Backport: Fix comment-empty-lines docstring (bug#35152)

* lisp/newcomment.el (comment-empty-lines): Consistently use US
commas in docstring.  Fix indentation of and typo in custom :type.

(cherry picked from commit 690c678f)
1 job for emacs-26 in 26 minutes and 23 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #1309
test

00:26:23