Help buffer link on name of customizable thing (at start of buffer)

[Drew Adams]

Suggestion for after the release -

In buffer *Help*, for help on a thing that is customizable, put the same
link on the name of the customizable thing (e.g. user variable or face), at
the beginning of the *Help* buffer, that is currently put on the word
"customize" at the bottom of the buffer.

Advantage: When you use, say, `C-v some-option', you can hit RET
immediately, to customize the thing, since the cursor is at `point-min' by
default. This is quicker than using, e.g., `M-x customize-option': instead
of `M-x customize-option RET foo RET', just use `C-h v foo RET RET'.

It also obviates any need for separate key bindings for `customize-this' and
`customize-that', as long as there is a binding for `describe-this' and
that. Being handy, this will quickly become a main entry point for
Customize, which is not a bad thing, IMO: a *Help* description, with the
current value shown, is a good place to start, before customizing something.

I don't see any reason not to do this. While the use of this link won't be
as obvious (but there would be a help tooltip) as the "You can customize
this variable" at the buffer bottom, users will learn and appreciate this
convenience.

We should also, obviously, keep the more explicit link at the bottom: "You
can customize this variable".

Also, the same form (i.e., the same *Help* buffer layout) should be used for
faces and user options. This is not the case now. Currently, `describe-face'
puts a "(customize this face)" link right after the face name, on the first
*Help* buffer line, whereas `describe-variable' puts a "You can customize
this variable" link at the bottom of the buffer, just before the [back]
button. The latter form is preferable, IMO.