[gtk-doc] Fix a typo.

[Stefan Sauer <stefkost src gnome org>]

commit 9584a32476a4f18e7431cbea4b10b47ead5214b3
Author: HorimotoYasuhiro <horimoto clear-code com>
Date:   Fri Apr 28 18:33:25 2017 +0900

    Fix a typo.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781888

 gtkdoc-fixxref.in |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtkdoc-fixxref.in b/gtkdoc-fixxref.in
index 1833a03..598a2ab 100755
--- a/gtkdoc-fixxref.in
+++ b/gtkdoc-fixxref.in
@@ -43,7 +43,7 @@ if __name__ == '__main__':
                         'in addition to HTML_DIR')
     parser.add_argument('--src-lang', default='c',
                         help='Programing language used for syntax highlighting. The'
-                        'available languages depend on the source source'
+                        'available languages depend on the source'
                         'highlighter you use.')
 
     options = parser.parse_args()