Add a comment on "invokables"

'Album\Controller\Album' => 'Album\Controller\AlbumController', is also a new line, but not mentioned in tutorial
Merge branch 'hotfix/zend-di-note'
Merge remote-tracking branch 'origin/pr/1321'

Close #1321
Merge remote-tracking branch 'origin/pr/1322'

Close #1322
Merge remote-tracking branch 'origin/pr/1325' into hotfix/1325
[#1325] Replaced comment with a line emphasis
Merge branch 'hotfix/1325' into develop

Forward port #1325