mu4e: update docs

mu4e/mu4e-helpers.el

@@ -46,11 +46,8 @@ When set, this should be a function that takes a file name and
 returns a string (icon) or nil.
 
 If you have the `nerd-icons' package, you can put
-`nerd-icons-icon-for-file'. If those icons are too big, consider
-installing the special nerd fonts, or perhaps use a value like:
-
-   (lambda (name)
-     (nerd-icons-icon-for-file name :height 1.0)))"
+`nerd-icons-icon-for-file' here; or with `all-the-icons', use
+`all-the-icons-icon-for-file'."
   :type '(choice (const :tag "None" nil) function)
   :group 'mu4e)
 

mu4e/mu4e.texi

@@ -3992,6 +3992,7 @@ with other tools.
 * BBDB::Hooking up with the Insidious Big Brother Database
 * Sauron::Getting new mail notifications with Sauron
 * Hydra:: Custom shortcut menus
+* Emojis:: Emojis for MIME-types
 @end menu
 
 @node Org-contacts
@@ -4155,6 +4156,20 @@ With Hydra installed, we can add multi-character shortcuts, for instance:
 Now, you can bind a convenient key to my-mu4e-bookmarks/body.
 @end lisp
 
+@node Nerd-icons
+@section Nerd-icons
+
+With packages such as
+@uref{https://github.com/rainstormstudio/nerd-icons.el,Nerd Icons} and
+@uref{https://github.com/domtronn/all-the-icons.el, All The Icons} you can use
+'emoji' icons in various places in Emacs; see the specific packages for details.
+
+@code{mu4e} has support for these in its message-view, where it can use the
+emojis to decorate the mime-types for attachments. You can enable this through
+the variable @code{mu4e-file-name-to-icon-function}, which you can set to e.g.,
+@code{all-the-icons-icon-for-file} or @code{nerd-icons-icon-for-file name}, for
+All-the-Icons and Nerd-Fonts, respectively.
+
 @node Example configurations
 @appendix Example configurations