Fix a copy/paste error in get_next_post_link() description and $format argument. props jim912, ounziw. fixes #25743.

git-svn-id: https://develop.svn.wordpress.org/trunk@25965 602fd350-edb4-49c9-b593-d223f7449a82
Restore @see get_next_post_link() reference and move it to next_post_link(). see #25743.

git-svn-id: https://develop.svn.wordpress.org/trunk@25966 602fd350-edb4-49c9-b593-d223f7449a82