Add magit-delta

Document a workaround for the issue seen in dandavison/magit-delta#13.

setup-files/setup-magit.el

@@ -1,4 +1,4 @@
-;; Time-stamp: <2021-09-27 13:45:50 kmodi>
+;; Time-stamp: <2021-10-22 13:28:59 kmodi>
 
 ;; Contents:
 ;;
@@ -349,6 +349,25 @@ It is assumed that the author has only one or two names."
                     magit-log-mode-hook))
       (add-hook hook #'emojify-turn-on-emojify-mode))))
 
+;; https://github.com/dandavison/magit-delta
+;; Requires the user to download the `delta' executable and put it somewhere
+;; in the PATH before starting emacs.
+;;
+;; Due to a current issue in delta, you cannot enable its `line-numbers' feature without
+;; messing up the diffs in magit. A workaround is that you can enable `side-by-side'
+;; mode. That shows line numbers in side-by-side mode in the terminal, but leaves
+;; `magit-delta' unaffected!
+;;
+;; [delta]
+;;     # https://github.com/dandavison/magit-delta/issues/13
+;;     # line-numbers = true    # Don't do this.. messes up diffs in magit
+;;     #
+;;     side-by-side = true      # Display a side-by-side diff view instead of the traditional view
+(when (executable-find "delta")
+  (use-package magit-delta
+    :ensure t
+    :hook (magit-mode . magit-delta-mode)))
+
 
 (provide 'setup-magit)