Update configuration.rst

the sonata_admin.templates section wasn't full (it's now aligned with Templates documentation page)
Update templates.rst

sonata_admin.templates.dashboard was missing
Merge pull request #1443 from net02/patch-2

Updated documentation
wrap nav menu in block for easier customization
Merge pull request #1441 from tiagojsag/menu_block

Wrap nav menu in block for easier customization
Merge branch 'sonata/master'