tweak(org): org-imenu-depth = 6

Headings beyond 6 are excessive in almost any org document, and only
muddy (and slow down) imenu search results, so I'm reducing it to the
number of available HTML headings.

modules/lang/org/config.el

@@ -115,7 +115,7 @@ Is relative to `org-directory', unless it is absolute. Is used in Doom's default
         org-fontify-whole-heading-line t
         org-hide-leading-stars t
         org-image-actual-width nil
-        org-imenu-depth 8
+        org-imenu-depth 6
         ;; Sub-lists should have different bullets
         org-list-demote-modify-bullet '(("+" . "-") ("-" . "+") ("*" . "+") ("1." . "a."))
         org-priority-faces