Fixed formatting, added note about work in progress

docs/guide/input-file-upload.md

-# Upload File with Yii2
+Uploading Files
+===============
 
-### First you need to create a model that will handle the form of download the file.
+> Note: This section is under development.
+
+First you need to create a model that will handle the form of download the file
+-------------------------------------------------------------------------------
 
 ```php
 namespace app\models;
@@ -29,9 +33,13 @@ class UploadForm extends Model
     }
 }
 ```
-In this code, we created a model ```UploadForm``` with an attribute ```$file``` that will be is ```<input type="file">``` in upload form and pointed out to him validation rule ```file```. This rule is [[yii\validators\FileValidator|FileValidator]]
 
-### Secondly create a view for our model.
+In this code, we created a model `UploadForm` with an attribute `$file` that will be is `<input type="file">` in upload
+form and pointed out to him validation rule `file`. This rule is [[yii\validators\FileValidator|FileValidator]].
+
+Secondly create a view for our model
+------------------------------------
+
 ```php
 <?php
 use yii\widgets\ActiveForm;
@@ -45,9 +53,12 @@ $form = ActiveForm::begin(['options' => ['enctype' => 'multipart/form-data']]);
 <?php ActiveForm::end(); ?>
 ```
 
-It is different attribute ```'enctype' => 'multipart/form-data'``` from the standard form. This value is required when you are using forms that have a file upload control. ```fileInput()``` represents a form input field.
+It is different attribute `'enctype' => 'multipart/form-data'` from the standard form. This value is required when you
+are using forms that have a file upload control. `fileInput()` represents a form input field.
+
+Thirdly, that create the controller that will connect our form and model
+------------------------------------------------------------------------
 
-### Thirdly, that create the controller that will connect our form and model.
 ```php
 namespace app\controllers;
 
@@ -74,26 +85,34 @@ class SiteController extends Controller
     }
 }
 ```
-The difference here from the standard crud action, so use ```UploadedFile::getInstance(...)``` instead ```model->load(...)```. [[\yii\web\UploadedFile|UploadedFile]] does not run the model validation, it only provides information about the uploaded file. Therefore, you need to run validation manually ```$model->validate()```. This triggers the [[yii\validators\FileValidator|FileValidator]] that expects a file
+
+The difference here from the standard crud action, so use `UploadedFile::getInstance(...)` instead `model->load(...)`.
+[[\yii\web\UploadedFile|UploadedFile]] does not run the model validation, it only provides information about the uploaded
+file. Therefore, you need to run validation manually `$model->validate()`. This triggers the
+[[yii\validators\FileValidator|FileValidator]] that expects a file
+
 ```php
 $file instanceof UploadedFile || $file->error == UPLOAD_ERR_NO_FILE //in code framework
 ```
 
 If validation done without errors, then save the file 
+
 ```php
 $model->file->saveAs('uploads/' . $model->file->baseName . '.' . $model->file->extension);
 ```
-If you use "basic" application then forlder ```uploads``` should be create inside ```web``` folder.
 
-Everything is ready, now run the page and download the file. Check the folder ```basic/web/uploads``` to make sure that you have downloaded.
+If you use "basic" application then forlder `uploads` should be create inside `web` folder.
 
-## Additional information.
+Everything is ready, now run the page and download the file. Check the folder `basic/web/uploads` to make sure that
+you have downloaded.
 
-***
+Additional information
+----------------------
 
 ### Required rule
 
-If you need to check the mandatory download the file, then use ```skipOnEmpty```.
+If you need to check the mandatory download the file, then use `skipOnEmpty`.
+
 ```php
 public function rules()
 {
@@ -103,17 +122,15 @@ public function rules()
 }
 ```
 
-***
-
 ### Path upload folder
 
-Folder to download the file can be installed using ```Yii::getAlias('@app/uploads')```. This base path of currently running application and folder ```uploads``
-
-***
+Folder to download the file can be installed using `Yii::getAlias('@app/uploads')`. This base path of currently running
+application and folder `uploads`.
 
 ### MIME type
 
-FileValidator have property ```$types```
+FileValidator has property `$types`
+
 ```php
 public function rules()
 {
@@ -122,16 +139,20 @@ public function rules()
     ];
 }
 ```
+
 it pulls
+
 ```php
 in_array(strtolower(pathinfo($file->name, PATHINFO_EXTENSION)), $this->types, true))
 ```
+
 As you can see, the name of the expansion may be one and the file type - other, actually.
 
-``UploadedFile::getInstance()->type``` also do not take this value for granted.
-Instead, use [[\yii\helpers\BaseFileHelper|FileHelper]] and his [[FileHelper::getMimeType()]] to determine the exact MIME type. 
+`UploadedFile::getInstance()->type` also do not take this value for granted. Instead, use
+[[\yii\helpers\BaseFileHelper|FileHelper]] and his [[FileHelper::getMimeType()]] to determine the exact MIME type. 
 
-If allowed to **load only the images**, using [[\yii\validators\ImageValidator|ImageValidator]] instead  [[yii\validators\FileValidator|FileValidator]].
+If allowed to **load only the images**, using [[\yii\validators\ImageValidator|ImageValidator]] instead
+ [[yii\validators\FileValidator|FileValidator]].
 
 ```php
 public function rules()
@@ -141,15 +162,13 @@ public function rules()
     ];
 }
 ```
-```ImageValidator``` use use ```yii\helpers\FileHelper;``` for check mime types. 
-[List Mime types](http://en.wikipedia.org/wiki/Internet_media_type#List_of_common_media_types)
 
-***
+`ImageValidator` use use `yii\helpers\FileHelper;` for check mime types. 
+[List Mime types](http://en.wikipedia.org/wiki/Internet_media_type#List_of_common_media_types)
 
 ### Multiple files uploader
 
-If you need download multiple files, you will need to alter slightly the controller and view.
-At first view:
+If you need download multiple files, you will need to alter slightly the controller and view. At first view:
 
 ```php
 <?php
@@ -172,18 +191,22 @@ if ($model->hasErrors()) { //it is necessary to see all the errors for all the f
 ```
 
 In fact the only difference is in the one row.
+
 ```php
 <?= $form->field($model, 'file[]')->fileInput(['multiple' => '']) ?>
 ```
+
 instead
+
 ```php
 <?= $form->field($model, 'file')->fileInput() ?>
 ```
 
-* ```['multiple' => '']``` - HTML <input> multiple Attribute
-* ```file[]``` vs ```file`` - need, otherwise UploadedFile sees only one file
+* `['multiple' => '']` - HTML <input> multiple Attribute
+* `file[]` vs `file` - need, otherwise UploadedFile sees only one file
 
 We now turn to the controller
+
 ```php
 namespace app\controllers;
 
@@ -230,6 +253,9 @@ class SiteController extends Controller
     }
 }
 ```
+
 Here the differences in:
-* ``` UploadedFile::getInstances($model, 'file');``` instead ``` UploadedFile::getInstance($model, 'file');```. First returns **all** uploaded files for the given model attribute, second - one.
+
+* `UploadedFile::getInstances($model, 'file');` instead `UploadedFile::getInstance($model, 'file');`. First returns
+   **all** uploaded files for the given model attribute, second - one.
 * All other differences follow from the first.