Don't show the ghci :? output in the user guide

The ghci command list is now much larger than it used to be, and it
tends to go out of sync with the docs anyway.

docs/users_guide/ghci.xml

@@ -34,53 +34,9 @@ Prelude>
 </screen>
 
     <para>There may be a short pause while GHCi loads the prelude and
-    standard libraries, after which the prompt is shown.  If we follow
-    the instructions and type <literal>:?</literal> for help, we
-    get:</para>
-
-<screen>
- Commands available from the prompt:
-
-   &lt;stmt&gt;                      evaluate/run &lt;stmt&gt;
-   :add &lt;filename&gt; ...         add module(s) to the current target set
-   :browse [*]&lt;module&gt;         display the names defined by &lt;module&gt;
-   :cd &lt;dir&gt;                   change directory to &lt;dir&gt;
-   :def &lt;cmd&gt; &lt;expr&gt;           define a command :&lt;cmd&gt;
-   :edit &lt;file&gt;                edit file
-   :edit                       edit last module
-   :help, :?                   display this list of commands
-   :info [&lt;name&gt; ...]          display information about the given names
-   :load &lt;filename&gt; ...        load module(s) and their dependents
-   :module [+/-] [*]&lt;mod&gt; ...  set the context for expression evaluation
-   :main [&lt;arguments&gt; ...]     run the main function with the given arguments
-   :reload                     reload the current module set
-
-   :set &lt;option&gt; ...           set options
-   :set args &lt;arg&gt; ...         set the arguments returned by System.getArgs
-   :set prog &lt;progname&gt;        set the value returned by System.getProgName
-   :set prompt &lt;prompt&gt;        set the prompt used in GHCi
-   :set editor &lt;cmd&gt;        set the command used for :edit
-
-   :show modules               show the currently loaded modules
-   :show bindings              show the current bindings made at the prompt
-
-   :ctags [&lt;file&gt;]             create tags file for Vi (default: "tags")
-   :etags [&lt;file&gt;]             create tags file for Emacs (default: "TAGS")
-   :type &lt;expr&gt;                show the type of &lt;expr&gt;
-   :kind &lt;type&gt;                show the kind of &lt;type&gt;
-   :undef &lt;cmd&gt;                undefine user-defined command :&lt;cmd&gt;
-   :unset &lt;option&gt; ...         unset options
-   :quit                       exit GHCi
-   :!&lt;command&gt;                 run the shell command &lt;command&gt;
-
- Options for ':set' and ':unset':
-
-    +r            revert top-level expressions after each evaluation
-    +s            print timing/memory stats after each evaluation
-    +t            print type after evaluation
-    -&lt;flags&gt;      most GHC command line flags can also be set here
-                         (eg. -v2, -fglasgow-exts, etc.)
-</screen>
+    standard libraries, after which the prompt is shown. As the banner
+    says, you can type <literal>:?</literal> to see the list of commands
+    available, and a half line description of each of them.</para>
 
     <para>We'll explain most of these commands as we go along.  For
     Hugs users: many things work the same as in Hugs, so you should be