Fix 'etc/DOC' for a few functions/variables

* src/term.c (Ftty_frame_at):
* src/menu.c (syms_of_menu) <x-popup-menu-function>:
* src/dispnew.c (Fredisplay): Fix "doc:".  The extra blank was
preventing 'make-docfile' from recognizing the functions and
variables and extracting their documentation to 'etc/DOC'.
(Bug#76722)

src/dispnew.c

@@ -6948,7 +6948,7 @@ sit_for (Lisp_Object timeout, bool reading, int display_option)
 
 
 DEFUN ("redisplay", Fredisplay, Sredisplay, 0, 1, 0,
-       doc : /* Perform redisplay.
+       doc: /* Perform redisplay.
 Optional arg FORCE exists for historical reasons and is ignored.
 Value is t if redisplay has been performed, nil if executing a
 keyboard macro.  */)

src/menu.c

@@ -1628,7 +1628,7 @@ won't be run if `x-popup-menu' fails or returns for some other reason
   Vx_pre_popup_menu_hook = Qnil;
 
   DEFVAR_LISP ("x-popup-menu-function", Vx_popup_menu_function,
-	       doc : /* Function to call to pop up a menu.
+	       doc: /* Function to call to pop up a menu.
  The function is called like `x-popup-menu'.  This is currently only
  used for frames on text terminals.  */);
   Vx_popup_menu_function = Qnil;

src/term.c

@@ -2673,7 +2673,7 @@ tty_frame_at (int x, int y, int *cx, int *cy)
 }
 
 DEFUN ("tty-frame-at", Ftty_frame_at, Stty_frame_at, 2, 2, 0,
-       doc : /* Return tty frame containing absolute pixel position (X, Y).
+       doc: /* Return tty frame containing absolute pixel position (X, Y).
 Value is nil if no frame found.  Otherwise it is a list (FRAME CX CY),
 where FRAME is the frame containing (X, Y) and CX and CY are X and Y
 relative to FRAME.  */)