Add structure-extensions.md to translate into Russian
structure-extensions.md is translated to Russian
fixes for translation of file 'structure-extensions.md' to Russian
fixes for translation of file 'structure-extensions.md' to Russian
Merge branch 'master' of https://github.com/maxmirazh33/yii2
Merge branch 'master' of git://github.com/yiisoft/yii2
Merge pull request #4804 from maxmirazh33/master

structure-extensions.md translated to Russian[skip-ci]