Fix formatting of recent Gnus nnselect changes

Fix formatting of recent Gnus nnselect changes

* doc/misc/gnus.texi (Finding the Parent, Selection Groups)
(Searching, Basic Usage): Heed sentence-end-double-space.  Fix
formatting of prose and examples.
* etc/NEWS: Fix typo.
* lisp/gnus/gnus-srvr.el: Remove disabled autoload.
* lisp/gnus/gnus-cloud.el (gnus-cloud-available-chunks):
* lisp/gnus/gnus-group.el (gnus-group-read-ephemeral-search-group):
* lisp/gnus/gnus-sum.el (gnus-refer-thread-use-search)
(gnus-summary-refer-thread):
* lisp/gnus/gnus.el (gnus-kill-ephemeral-group):
* lisp/gnus/nnheader.el (nnheader-head-make-header)
(nnheader-parse-head):
* lisp/gnus/nnir.el:
(nnir-hyrex-remove-prefix, nnir-run-notmuch):
* lisp/gnus/nnselect.el: Fix formatting/indentation of commentary,
docstring, and/or code.