Add command in eww to toggle images

* lisp/net/eww.el (eww-toggle-images): New function.
(eww-mode-map): Add key binding and menu entry.
* lisp/net/shr.el (shr-inhibit-images): Make it customizable.
* doc/misc/eww.texi (Basics): Document eww-toggle-images.
Fix index entries for shr-use-fonts and shr-use-colors.
(Advanced): Document shr-inhibit-images
(bug#47705).

lisp/net/eww.el

@@ -987,6 +987,7 @@ the like."
     (define-key map "F" 'eww-toggle-fonts)
     (define-key map "D" 'eww-toggle-paragraph-direction)
     (define-key map [(meta C)] 'eww-toggle-colors)
+    (define-key map [(meta I)] 'eww-toggle-images)
 
     (define-key map "b" 'eww-add-bookmark)
     (define-key map "B" 'eww-list-bookmarks)
@@ -1015,6 +1016,7 @@ the like."
 	["List cookies" url-cookie-list t]
 	["Toggle fonts" eww-toggle-fonts t]
 	["Toggle colors" eww-toggle-colors t]
+	["Toggle images" eww-toggle-images t]
         ["Character Encoding" eww-set-character-encoding]
         ["Toggle Paragraph Direction" eww-toggle-paragraph-direction]))
     map))
@@ -1893,6 +1895,14 @@ If CHARSET is nil then use UTF-8."
 	     "off"))
   (eww-reload))
 
+(defun eww-toggle-images ()
+  "Toggle whether or not to display images."
+  (interactive nil eww-mode)
+  (setq shr-inhibit-images (not shr-inhibit-images))
+  (eww-reload)
+  (message "Images are now %s"
+           (if shr-inhibit-images "off" "on")))
+
 ;;; Bookmarks code
 
 (defvar eww-bookmarks nil)

lisp/net/shr.el

@@ -183,8 +183,10 @@ temporarily blinks with this face."
   "Face for <abbr> elements."
   :version "27.1")
 
-(defvar shr-inhibit-images nil
-  "If non-nil, inhibit loading images.")
+(defcustom shr-inhibit-images nil
+  "If non-nil, inhibit loading images."
+  :version "28.1"
+  :type 'boolean)
 
 (defvar shr-external-rendering-functions nil
   "Alist of tag/function pairs used to alter how shr renders certain tags.