bug#36826: 26.1; request: add variable value editing feature to the *Help* buffer

[Drew Adams]

> When doing a C-h v the Help buffer shows
> the value of the variable and also its documentation.
>
> Bind the currently unused key 'e' to edit the
> variable's value, maybe in a separate popup
> buffer if the value is complex. E.g. the user
> presses e, the value pops up rendered in
> editable lisp format, the user edits it in place,
> presses C-c C-c and the variable is set
> to the new value.

I would say this isn't really needed or that helpful.
(Just one opinion.)

1. If the variable is a user option then:
   a. `*Help*' already shows a link to the Customize
      buffer, which is the proper place to change
      the value (and possibly save it).
   b. With the cursor on the option name in `*Help*',
      `M-x set-variable' defaults to the option name.

2. If the variable is not a user option, it may
   be buffer-local.  Does the user want to set the
   value in the current buffer or set the default
   value of the variable?  The behavior is different.

3. It's not hard to use `M-: (setq ...)' or
   `M-: (setq-default ...)' to set the new value.
   And it's not hard to copy the current value to
   the `setq(-default)' sexp and edit it there.