Allow enabling xwidget-webkit-edit-mode via a binding

* doc/emacs/misc.texi: Document changes.
* lisp/xwidget.el (xwidget-webkit-mode-map): Add shortcut for
xwidget-webkit-edit-mode.

doc/emacs/misc.texi

@@ -2961,6 +2961,9 @@ make those characters and other common editing keys insert themselves
 when pressed, you can enable @code{xwidget-webkit-edit-mode}, which
 redefines them to be passed through to the WebKit xwidget.
 
+You can also enable @code{xwidget-webkit-edit-mode} by typing @kbd{e}
+inside the xwidget webkit buffer.
+
 @node Browse-URL
 @subsection  Following URLs
 @cindex World Wide Web

lisp/xwidget.el

@@ -146,6 +146,7 @@ in `split-window-right' with a new xwidget webkit session."
     (define-key map "w" 'xwidget-webkit-current-url)
     (define-key map "+" 'xwidget-webkit-zoom-in)
     (define-key map "-" 'xwidget-webkit-zoom-out)
+    (define-key map "e" 'xwidget-webkit-edit-mode)
 
     ;;similar to image mode bindings
     (define-key map (kbd "SPC")                 'xwidget-webkit-scroll-up)