removed obsolete internal docs

docs/guide/basic-autoloading.md

@@ -3,10 +3,12 @@ Autoloading
 
 > Note: This chapter is under development.
 
-All classes, interfaces and traits are loaded automatically at the moment they are used. There's no need to use `include` or `require`. It is true for Composer-loaded packages as well as Yii extensions.
+All classes, interfaces and traits are loaded automatically at the moment they are used.
+There's no need to use `include` or `require`. It is true for Composer-loaded packages as well as Yii extensions.
 
-Yii's autoloader works according to [PSR-4](https://github.com/php-fig/fig-standards/blob/master/proposed/psr-4-autoloader/psr-4-autoloader.md).
+Yii's autoloader works according to the [PSR-4 standard](https://github.com/php-fig/fig-standards/blob/master/proposed/psr-4-autoloader/psr-4-autoloader.md).
-That means namespaces, classes, interfaces and traits must correspond to file system paths and file names accordinly, except for root namespace paths that are defined by an alias.
+That means namespaces, classes, interfaces and traits must correspond to file system paths and file names accordingly,
+except for root namespace paths that are defined by an alias.
 
 For example, if the standard alias `@app` refers to `/var/www/example.com/` then `\app\models\User` will be loaded from `/var/www/example.com/models/User.php`.
 

docs/internals/autoloader.md

@@ -1,19 +0,0 @@
-Yii2 class loader
-=================
-
-Yii 2 class loader is PSR-4 compliant. That means it can handle most of the PHP
-libraries and frameworks out there.
-
-In order to autoload a library you need to set a root alias for it.
-
-PEAR-style libraries
---------------------
-
-```php
-\Yii::setAlias('@Twig', '@app/vendors/Twig');
-```
-
-References
-----------
-
-- BaseYii::autoload

docs/internals/database.md

@@ -1,27 +0,0 @@
-Working with Database
-=====================
-
-Architecture
-------------
-
-### Data Access Object (DAO)
-
-* Connection
-* Command
-* DataReader
-* Transaction
-
-### Schema
-
-* TableSchema
-* ColumnSchema
-
-### Query Builder
-
-* Query
-* QueryBuilder
-
-### ActiveRecord
-
-* ActiveRecord
-* ActiveQuery