updated docs about plural rules

docs/guide/tutorial-i18n.md

@@ -233,32 +233,33 @@ Will produce "You are here for 47 sec. already!".
 
 #### Plurals
 
-Different languages have different ways to inflect plurals. Some rules are very complex so it's very handy that this
-functionality is provided without the need to specify inflection rule. Instead it only requires your input of inflected
-words in certain situations.
+Different languages have different ways to inflect plurals. Yii provides a convenient way for translating messages in
+different plural forms that works well even for very complex rules. Instead of dealing with the inflection rules directly
+it is sufficient to provide the translation of inflected words in certain situations only.
 
 ```php
-echo \Yii::t('app', 'There {n, plural, =0{are no cats} =1{is one cat} other{are # cats}}!', ['n' => 0]);
+echo \Yii::t('app', 'There {n, plural, =0{are no cats} =1{is one cat} other{are # cats}}!', ['n' => $n]);
 ```
 
-Will give us "There are no cats!".
+Will give us
 
-In the plural rule arguments above `=0` means exactly zero, `=1` stands for exactly one `other` is for any other number.
-`#` is replaced with the `n` argument value. It's not that simple for languages other than English. Here's an example
+- "There are no cats!" for `$n = 0`,
+- "There is one cat!" for `$n = 1`,
+- and "There are 42 cats!" for `$n = 42`.
+
+In the plural rule arguments above `=0` means exactly zero, `=1` stands for exactly one, and `other` is for any other number.
+`#` is replaced with the value of `n`. It's not that simple for languages other than English. Here's an example
 for Russian:
 
 ```
 Здесь {n, plural, =0{котов нет} =1{есть один кот} one{# кот} few{# кота} many{# котов} other{# кота}}!
 ```
 
-In the above it worth mentioning that `=1` matches exactly `n = 1` while `one` matches `21` or `101`.
-
-Note that if you are using a placeholder twice and one time it's used as `plural` another one should be used as `number` else
-you'll get "Inconsistent types declared for an argument: U_ARGUMENT_TYPE_MISMATCH" error:
+In the above it's worth mentioning that `=1` matches exactly `n = 1` while `one` matches `21` or `101`.
 
-```
-Total {count, number} {count, plural, one{item} other{items}}.
-```
+Note, that you can not use the Russian example in `Yii::t()` directly, you have to adjust the
+[[yii\base\Application::$sourceLanguage|source language]] setting in your application config
+so that Yii knows which language you are using to apply the correct plural rules.
 
 To learn which inflection forms you should specify for your language you can referrer to the
 [rules reference at unicode.org](http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html).