bug#21594: 25.0.50; (elisp): node `Variable Definitions' is not reachable by `i variable definition'

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

> I'm not quite sure what you want to have done here.  As you say, that
> node isn't really about "variable definitions", so it seems like a very
> good thing that "variable definition" doesn't take you there, but to
> "12.5 Defining Global Variables", which makes more sense.

Index entry `variable definition' takes you to 12.5,
and it did previously as well.  That's good, as far
as it goes.

The point of the bug report is this:

Node `Variable Definitions' is misnamed.  It is
only about _option_ definitions.  It does not
correspond to index entry `variable definitions'
(which is a good thing).

The title in the node itself is better: `Defining
Customization Variables'.  Please consider making
a change like that for the node itself (but see
below, for a node name that's arguably better).

(Someone looking for variable definitions, i.e.,
defining variables, and who might, therefore, use
index entry `variable definitions', will not find
anything about user options (`defcustom').

That's unfortunate perhaps, but there's no way
around that if we want a book (a tree, not a graph),
and we want the `defcustom' info to be where it is
now, which makes sense.

At least a user will find a link in node `Defining
Variables', to go to node `Variable Definitions'
for info about `defcustom'.)

The requested change is to the node name of
`Variable Definitions'.  Consider changing it to
`Defining User Options' or `Defining Customization
Variables'.

(But we don't really call them by the latter name.
When we use "variable" instead of "option" for
them we usually say "custom variable" or
"customizable variable".)