docs: simplify internal docs links

Fewer links means less confusion.

- Merge doom-issue and doom-commit links into doom-ref (for auto-linking
  Issue/PR/commit references).
- Merge doom-module-source and doom-docs-source links into doom-source.
- Rename doom-report-issue to doom-report.
- Use '!' as the icon for module issues link.
- Remove doom-repo (replaced with "doom:*" in :lang org module).
- Add doomdir and emacsdir links to :lang org module.

modules/lang/org/config.el

@@ -498,7 +498,10 @@ relative to `org-directory', unless it is an absolute path."
             '("gmap"        . "https://maps.google.com/maps?q=%s")
             '("duckduckgo"  . "https://duckduckgo.com/?q=%s")
             '("wikipedia"   . "https://en.wikipedia.org/wiki/%s")
-            '("wolfram"     . "https://wolframalpha.com/input/?i=%s"))
+            '("wolfram"     . "https://wolframalpha.com/input/?i=%s")
+            '("doom"        . "https://github.com/hlissner/doom-emacs/%s")
+            `("emacsdir"    . ,(doom-path doom-emacs-dir "%s"))
+            `("doomdir"     . ,(doom-path doom-private-dir "%s")))
 
   (+org-define-basic-link "org" 'org-directory)