Add line breaks before most form field descriptions (the italicized gray text...

Add line breaks before most form field descriptions (the italicized gray text on General Settings and other screens). props johnbillion, helenyhou, fixes #17390.


git-svn-id: https://core.svn.wordpress.org/trunk@20605 1a063a9b-81f0-0310-95a4-ce76da25c4cd