as discussed before, better do this change before RC to avoid breaking BC in GA.

related to #5214

[skip ci] Исправление смысловых, орфографических и грамматических ошибок/опечаток в /docs/guide-ru/concept-aliases.md

[skip ci] Fix double specification of basePath

[ci skip] more on update old docs

[skip ci] [SK] Updated locale strings

OK，那我merge先，不过我已经把图片放进来了，这个库本来也不是给人看的，应该看官方库，那边的才会更准确一些。
yii2-chinesization/yii2的不需要放图片，地址也最好别放绝对路径，因为文档后期是通过官方开发的apidoc软件渲染，而不是通过GitHub观看的。

[skip ci] Fix minor typo in assets docs

[skip ci] Added Czech translation

[skip ci] Add comment to documentation sample code

Add comment to documentation sample code for GridView

Update start-installation.md

update to 20140919 from English version

update to 20140919 from English version

update to 20140919 from English version

[ci skip] Ukrainian message translation