Rename `xref-pop-marker-stack` to `xref-go-back` (bug#38797)

It is the natural name after the addition of `xref-go-forward`.
The old name is retained as an alias.

* lisp/progmodes/xref.el (xref-pop-marker-stack): Rename.
(xref-go-forward, xref-quit-and-pop-marker-stack)
(xref-find-definitions):
* lisp/menu-bar.el (menu-bar-goto-menu):
* lisp/progmodes/etags.el (find-tag-marker-ring, pop-tag-mark):
* lisp/progmodes/prog-mode.el (prog-context-menu):
* doc/emacs/maintaining.texi (Looking Up Identifiers):
* etc/NEWS:
Use the new name.

1 files changed, 2 insertions, 2 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 2d5276dbd64..6d3256959ea 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -185,8 +185,8 @@ a prefix argument which is interpreted to mean "include all files".
 
 +++
 *** New command 'xref-go-forward'.
-It is bound to 'C-M-,' and jumps to the location where 'xref-pop-marker-stack'
-was invoked previously.
+It is bound to 'C-M-,' and jumps to the location where 'xref-go-back'
+('M-,', also known as 'xref-pop-marker-stack') was invoked previously.
 
 ** File notifications