Clearer instructions on what to look for in main-local.php when configuring the db param

fixes #7042

issue #7040

small punctation and syntax changes.

close #7024

in previous example this
Url::to(['post/index', 'year' => 2014, 'category' => 'php']) 
will not create `/index.php/posts/2014/php` 
because it will be handled by first find rule 'posts' => 'post/index' and url will be '/index.php/posts?year=2014&category=php'

fixes #7013

There is no queryRow! There must be queryOne in Yii2
am i right?!

only the phpManager configuration was described, the DbManager configuration was not found on this documentation

close #6771

formatting date and time values for years >=2038 or <=1901 is now possible also with intl extension is
installed. 32bit systems will fall back to the PHP implementation because intl uses a 32bit UNIX timestamp internally.
On a 64bit system the intl formatter is used in all cases if installed.

fixes #5577

fixes #6760