fixes #1674: Updated contributing docs

CONTRIBUTING.md

 Contributing to Yii2
 ====================
 
-Creating issues
----------------
-
-- Please use English if possible.
+- [Report an issue](docs/internals/report-an-issue.md)
+- [Traslate documentation or messages](docs/internals/translations.md)
+- [Contribute to the core code or fix bugs](docs/internals/getting-started.md)
\ No newline at end of file
-- Make sure it is clear how to reproduce it.
-- Make sure it is clear why you think it is necessary to fix.
-
-Contributing to the core framwork and official extensions
----------------------------------------------------------
-
-- [Getting started with Yii2 development](docs/internals/getting-started.md)
-- [Git workflow for Yii 2 contributors](docs/internals/git-workflow.md)
-- [Translation workflow](docs/internals/translations.md)

docs/internals/ar.md

-ActiveRecord
-============
-
-Scenarios
----------
-
-Possible scenario formats supported by ActiveRecord:
-
-```php
-public function scenarios()
-{
-    return [
-        // attributes array, all operations won't be wrapped with transaction
-        'scenario1' => ['attribute1', 'attribute2'],
-
-        // insert and update operations will be wrapped with transaction, delete won't be wrapped
-        'scenario2' => [
-            'attributes' => ['attribute1', 'attribute2'],
-            'atomic' => [self::OP_INSERT, self::OP_UPDATE],
-        ],
-    ];
-}
-```
-
-Query
------
-
-### Basic Queries
-
-### Relational Queries
-
-### Scopes

docs/internals/getting-started.md

@@ -29,4 +29,7 @@ If you're not core developer or want to use your own fork for pull requests:
   url = git://github.com/username/yii2.git
 ```
 
-> Hint: The workflow of forking a package and pushing changes back into your fork and then sending a pull-request to the maintainer is the same for all extensions you require via composer.
+> Hint: The workflow of forking a package and pushing changes back into your fork and then sending a pull-request to the
+  maintainer is the same for all extensions you require via composer.
+
+Please refer to [Git workflow for Yii 2 contributors](git-workflow.md) for details about creating pull requests.
\ No newline at end of file

docs/internals/report-an-issue.md

+Creating issues
+===============
+
+You got into rough corner while working with yii, or you found a bug? We are very sorry for that, but we can sort that
+out together.
+
+- If you are unsure about a function, you may ask on IRC or the forums. If the documentation is unclear, open a separate
+  issue.
+- Please use English if possible.
+- Make sure it is clear what is the problem and how to reproduce it.
+
+If you are going to report security issue please **do not** use the issue tracker and instead
+[contact us directly](http://www.yiiframework.com/security/).
+