[metacity] Revert spelling fix and add quotation marks

[Piotr Drąg <piotrdrag src gnome org>]

commit 41c908225a19b22a2f35b7cb47a902402ba95053
Author: Piotr Drąg <piotrdrag gmail com>
Date:   Thu Dec 15 18:41:29 2016 +0100

    Revert spelling fix and add quotation marks
    
    To make it clear that these are command line arguments.

 theme-viewer/theme-viewer-main.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/theme-viewer/theme-viewer-main.c b/theme-viewer/theme-viewer-main.c
index f0ba6a5..4f184b8 100644
--- a/theme-viewer/theme-viewer-main.c
+++ b/theme-viewer/theme-viewer-main.c
@@ -29,7 +29,7 @@ static GOptionEntry entries[] =
 {
   {
     "theme-type", 0, G_OPTION_FLAG_NONE, G_OPTION_ARG_STRING, &theme_type,
-    N_("Theme type to use (GTK+ or Metacity)"), N_("TYPE")
+    N_("Theme type to use (\"gtk\" or \"metacity\")"), N_("TYPE")
   },
   {
     "theme-name", 0, G_OPTION_FLAG_NONE, G_OPTION_ARG_STRING, &theme_name,