emacs: Fix the autoload comments

Remove them from non-top-level entry points, (such as the functions to
set notmuch modes and the deprecated notmuch-folder function). And add
one to the notmuch-hello function. Also, add missing documentation
string to notmuch-hello.

emacs/notmuch-hello.el

@@ -317,7 +317,9 @@ Complete list of currently available key bindings:
  ;;(setq buffer-read-only t)
 )
 
+;;;###autoload
 (defun notmuch-hello (&optional no-display)
+  "Run notmuch and display saved searches, known tags, etc."
   (interactive)
 
   ; Jump through a hoop to get this value from the deprecated variable
@@ -513,7 +515,6 @@ Complete list of currently available key bindings:
       (unless (widget-at)
 	(notmuch-hello-goto-search)))))
 
-;;;###autoload
 (defun notmuch-folder ()
   "Deprecated function for invoking notmuch---calling `notmuch' is preferred now."
   (interactive)

emacs/notmuch-show.el

@@ -586,7 +586,6 @@ function is used. "
       "Keymap for \"notmuch show\" buffers.")
 (fset 'notmuch-show-mode-map notmuch-show-mode-map)
 
-;;;###autoload
 (defun notmuch-show-mode ()
   "Major mode for viewing a thread with notmuch.
 

emacs/notmuch.el

@@ -329,7 +329,6 @@ For a mouse binding, return nil."
   "Face used in search mode face for tags."
   :group 'notmuch)
 
-;;;###autoload
 (defun notmuch-search-mode ()
   "Major mode displaying results of a notmuch search.