doc fix

Fixed sequence id match for postgresql

PgAdmin generates   sequence as  '"Schema"."Table_seq"'::regclass  when
non public schema is used.

Fixes #1499: Added `ActionColumn::controller` property to support customizing the controller for handling GridView actions

Added support for tagName and encodeLabel parameters in ButtonDropdown

changed install to create-project, added hint

Small correction in DB\Query comments

I checked this using XDebug, and the function actually returns null (which is something different than false). I assume it is the comment that should be changed, and not the code itself...