bug#1764: Names of shells in sh-ancestor-alist docstring

[Ulrich Mueller]

> I've checked in your fix.  Thanks.

Could you also add the following (I had already mentioned it above,
but without a patch).

--- emacs-orig/lisp/progmodes/sh-script.el
+++ emacs/lisp/progmodes/sh-script.el
@@ -249,7 +249,7 @@
 rc             Plan 9 Shell
   es           Extensible Shell
 sh             Bourne Shell
-  ash          ? Shell
+  ash          Almquist Shell
   jsh          Bourne Shell with Job Control
     bash       GNU Bourne Again Shell
     ksh88      Korn Shell '88