typo fix in gii.md
small typo fix

change usual code style to php code style
doc fix.
Fixes #2775: Added `yii\base\Application::bootstrap` to support running bootstrap classes when starting an application
updated composer documentation
Merge commit '1ccad3d97db122b71b84f222807e547b86687a12' into feature/composer-docs
Update controller.md
Merge remote-tracking branch 'upstream/master'