Add another potential fix for icon misalignment in doom-modeline (#5017)

I've added the code I used to finally fix modeline icon misalignment
problems in my own setup as a suggestion in the Troubleshooting section.

modules/ui/modeline/README.org

@@ -72,12 +72,12 @@ I believe the consensus is: this is due to oversized icons, i.e. a font issue. S
 
 2. Add some padding to the modeline definition:
 
-    #+BEGIN_SRC elisp
+    #+begin_src elisp
     (after! doom-modeline
       (doom-modeline-def-modeline 'main
         '(bar matches buffer-info remote-host buffer-position parrot selection-info)
         '(misc-info minor-modes checker input-method buffer-encoding major-mode process vcs "  "))) ; <-- added padding here
-    #+END_SRC
+    #+end_src
 
 3. Use another font for the mode line (or a different ~:height~) (source)
 
@@ -89,6 +89,24 @@ I believe the consensus is: this is due to oversized icons, i.e. a font issue. S
 
 (Mentioned in #1680, #278 and seagle0128/doom-modeline#334)
 
+4. Change the width of icon characters in ~char-width-table~:
+   
+    #+BEGIN_SRC elisp
+    (add-hook! 'doom-modeline-mode-hook
+      (let ((char-table char-width-table))
+        (while (setq char-table (char-table-parent char-table)))
+        (dolist (pair doom-modeline-rhs-icons-alist)
+          (let ((width 2)  ; <-- tweak this
+                (chars (cdr pair))
+                (table (make-char-table nil)))
+            (dolist (char chars)
+              (set-char-table-range table char width))
+            (optimize-char-table table)
+            (set-char-table-parent table char-table)
+            (setq char-width-table table)))))
+    #+END_SRC
+
+   If this doesn't help, try different values for ~width~ such as ~width 1~ or ~width 3~. 
 
 * Appendix
 ** Autodefs