docs/faq: expand "how to change line numbers"

docs/faq.org

@@ -767,9 +767,21 @@ e.g.
 
 ** How do I change the style of line-numbers (or disable them altogether)?
 Doom uses the ~display-line-numbers~ package, which is built into Emacs 26+.
+
+#+begin_quote
 This package has been backported for Emacs 25 users, but is powered by =nlinum=
 there (which will be removed when we drop 25 support).
+#+end_quote
 
+*** Disabling line numbers entirely
+#+BEGIN_SRC elisp
+(setq display-line-numbers-type nil)
+;; or
+(remove-hook! '(prog-mode-hook text-mode-hook conf-mode-hook)
+              #'display-line-numbers-mode)
+#+END_SRC
+
+*** Switching to relative line numbers (permanently)
 To change the style of line numbers, change the value of the
 ~display-line-numbers-type~ variable. It accepts =t= (normal line numbers),
 ='relative= (relative line numbers), ='visual= (relative line numbers in screen
@@ -782,9 +794,11 @@ display-line-numbers-type= or =C-h v display-line-numbers-type=.
 The ~'visual~ option is unavailable in Emacs 25.
 #+end_quote
 
-There is also ~M-x doom/toggle-line-numbers~ (bound to =SPC t l= by default) for
-cycling through the available line number styles in the current buffer. eg. =t
--> relative -> nil -> t=.
+*** Switching the style of line numbers (temporarily)
+Use ~M-x doom/toggle-line-numbers~ (bound to =SPC t l= by default) to cycle
+through the available line number styles in the current buffer.
+
+e.g. =normal -> relative -> visual -> disabled -> normal=.
 
 ** How do I change the behavior and appearance of popup windows?
 The =:ui popup= module tries to standardize how Emacs handles "temporary"