nit: minor reformatting & revision

Also corrects the version string of obsolete variable `+mu4e-backend`.

modules/ui/indent-guides/config.el

@@ -45,6 +45,8 @@ be enabled. If any function returns non-nil, the mode will not be activated."
   ;; TODO: Uncomment once we support treesit
   ;; (setq indent-bars-treesit-support (modulep! :tools tree-sitter))
 
+  ;; indent-bars adds this to `enable-theme-functions', which was introduced in
+  ;; 29.1, which will be redundant with `doom-load-theme-hook'.
   (unless (boundp 'enable-theme-functions)
     (add-hook 'doom-load-theme-hook #'indent-bars-reset-styles))
 

modules/ui/indent-guides/packages.el

@@ -3,4 +3,4 @@
 
 (package! indent-bars
   :recipe (:host github :repo "jdtsmith/indent-bars")
-   :pin "c8376cf4373a6444ca88e88736db7576dedb51d6")
+  :pin "c8376cf4373a6444ca88e88736db7576dedb51d6")