virsh: update help for "virsh help help"

As virsh help supports both command and command group now,
update "cmdHelp" to print consite help, (this patch is
increment of "78290527").

And also remove redundant empty line in "vshUsage".

* tools/virsh.c

tools/virsh.c

@@ -562,13 +562,15 @@ vshReconnect(vshControl *ctl) {
  */
 static const vshCmdInfo info_help[] = {
     {"help", N_("print help")},
-    {"desc", N_("Prints global help or command specific help.")},
+    {"desc", N_("Prints global help, command specific help, or help for a\n"
+                "    group of related commands")},
 
     {NULL, NULL}
 };
 
 static const vshCmdOptDef opts_help[] = {
-    {"command", VSH_OT_DATA, 0, N_("name of command")},
+    {"command", VSH_OT_DATA, 0, N_("Prints global help or command specific help.")},
+    {"group", VSH_OT_DATA, 0, N_("Prints global help or help for a group of related commands.")},
     {NULL, 0, 0, NULL}
 };
 
@@ -577,7 +579,12 @@ cmdHelp(vshControl *ctl, const vshCmd *cmd)
  {
     const vshCmdDef *c;
     const vshCmdGrp *g;
-    const char *name = vshCommandOptString(cmd, "command", NULL);
+    const char *name;
+
+    name = vshCommandOptString(cmd, "command", NULL);
+
+    if (!name)
+        name = vshCommandOptString(cmd, "group", NULL);
 
     if (!name) {
         const vshCmdGrp *grp;
@@ -596,8 +603,8 @@ cmdHelp(vshControl *ctl, const vshCmd *cmd)
             vshPrint(ctl, "\n");
         }
 
-         return TRUE;
-     }
+        return TRUE;
+    }
 
     if ((c = vshCmddefSearch(name))) {
         return vshCmddefHelp(ctl, name);