Doc and comment fixes re "online" help

Doc and comment fixes re "online" help

* doc/emacs/help.texi (Misc Help):
* doc/emacs/trouble.texi (Checklist):
* doc/lispintro/emacs-lisp-intro.texi (Note for Novices, Finding More)
(Conclusion):
* doc/lispref/help.texi (Help Functions):
* doc/misc/info.texi, doc/misc/mh-e.texi:
* etc/refcards/calccard.tex (section{Getting Help}):
* lisp/cus-edit.el (help):
* lisp/finder.el (finder-known-keywords):
* lisp/help.el (help-for-help-internal):
* lisp/vc/ediff-mult.el (ediff-meta-buffer-verbose-message)
(ediff-redraw-registry-buffer):
* lisp/vc/ediff-ptch.el (ediff-patch-file-internal):
Doc fixes re "online" help.

Fixes: debbugs:17803