bug#36417: [PATCH] Document bookmark annotations in Emacs Manual

[Drew Adams <drew.adams@oracle.com>]

> Btw, what is the use case for using annotations but not showing them?
> If that use case is not important enough, perhaps we shouldn't mention
> the second option.

Showing a bookmark's annotation means displaying
it (in its own buffer).

Option `bookmark-automatically-show-annotations'
is about _automatically_ showing annotations
whenever bookmarks are jumped to.  If it is nil
then a bookmark's annotation is shown (displayed)
only on demand.

Option `bookmark-use-annotations" non-nil means
that a buffer is opened for you to add an
annotation, if none exists, or edit an existing
annotation, whenever a bookmark is set.

One is about showing annotations when bookmarks
are jumped to.  The other is about editing (and
creating) annotations whenever bookmarks are set
(created or updated).

It is true that the doc string for
`bookmark-use-annotations' mistakenly currently
says `saving' instead of `setting'.  That, at
least, should be corrected.