[gtk-doc] Fixed another typo in string...

[Daniel Mustieles García <dmustieles src gnome org>]

commit 60d384bf6b2e074054168c065fba83da61de69f2
Author: Daniel Mustieles <daniel mustieles gmail com>
Date:   Tue Feb 11 10:26:19 2014 +0100

    Fixed another typo in string...

 help/manual/C/index.docbook |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/help/manual/C/index.docbook b/help/manual/C/index.docbook
index 8e41acd..5218c33 100644
--- a/help/manual/C/index.docbook
+++ b/help/manual/C/index.docbook
@@ -829,7 +829,7 @@ gtkdoc-fixxref --module=$(DOC_MODULE) --module-dir=html
       </para>
 
       <para>
-        Since GTK-Doc-1.18 the tool supports a subset or the
+        Since GTK-Doc-1.18 the tool supports a subset of the
         <ulink url="http://daringfireball.net/projects/markdown/";>markdown language</ulink>.
         The support has improved a lot with version 1.20. On older GTK-Doc
         versions the content will be rendered as it (the list items will appear