docs: Mention icons type and nerd-icons

README.org

@@ -133,6 +133,10 @@
    #+BEGIN_SRC emacs-lisp :tangle yes
     (setq centaur-tabs-set-icons t)
    #+END_SRC
+   Make sure you have set the icon type
+   #+BEGIN_SRC emacs-lisp :tangle yes
+    (setq centaur-tabs-icon-type 'all-the-icons)  ; or 'nerd-icons
+   #+END_SRC
 ** Plain icons
    To make icons plain (same color as tabs' text):
    #+BEGIN_SRC emacs-lisp :tangle yes
@@ -541,8 +545,8 @@ Other buffer group by `centaur-tabs-get-group-name' with project name."
 * Common issues
 ** Icons not showing
 If the icons in your tabs are not showing, it is likely because of one of the two following reasons:
-***  all-the-icons not installed
-If [[https://github.com/domtronn/all-the-icons.el][all-the-icons]] is not installed properly, your mode icons won't show up. To solve this issue, you have to install all-the-icons and follow the instructions indicated in its repository.
+***  =all-the-icons= / =nerd-icons= not installed
+If [[https://github.com/domtronn/all-the-icons.el][all-the-icons]] or [[https://github.com/rainstormstudio/nerd-icons.el][nerd-icons]] is not installed properly, your mode icons won't show up. To solve this issue, you have to install all-the-icons and follow the instructions indicated in its repository.
 *** Font with required unicode symbols missing
 If you get something like the following image in your tabs: