Fix documentation

Fix documentation

* doc/org.texi (Conventions): Remove unhelpful and wrong footnote.
(Initial visibility): Remove spurious paragraph.
(Global and local cycling):
(Motion): Fix function name.
(Plain lists): Reverse prefix argument action.
(Column width and alignment):
(Column groups):
(Tag inheritance):
(Tag hierarchy):
(The date/time prompt): Fix typo
(Link abbreviations):
(Tag searches):
(Timers): Fix wording.
(Checkboxes): Improve accuracy of footnote.  Correctly describe the
behaviour of `org-toggle-checkbox' on a headline.
(Filtering/limiting agenda items): More accurate description for `+' and
`-'.  Also remove unused `\' key.
(Agenda commands): Fix behaviour description.

* lisp/org-agenda.el (org-agenda-filter-by-tag): Fix docstring
  appearance.
(org-agenda-show-and-scroll-up): Fix wording.

* lisp/org-id.el (org-id-link-to-org-use-id): Fix function name.
(org-id-update-id-locations): Remove reference to unused argument.

* lisp/org.el (org-insert-heading): Improve docstring.
(org-insert-todo-heading): Describe behavior on a plain list item.
(org-update-statistics-cookies): Describe behavior when called with
a prefix argument.
(org-metaright): Fix typo.
(org-kill-note-or-show-branches): Fix function name.
(org-yank): Fix wording.

Reported-by: Jorge <jorge13515@gmail.com>
<http://permalink.gmane.org/gmane.emacs.orgmode/109428>