[gtksourceviewmm] Update README to match the gtksourceview version

[Murray Cumming <murrayc src gnome org>]

commit 00c04c3beb661f4a29544efcdb606bc2965eb5f4
Author: Christoph Brill <egore911 gmail com>
Date:   Sun May 10 07:04:36 2015 +0200

    Update README to match the gtksourceview version

 README |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/README b/README
index 6b34e6d..7fa9a74 100644
--- a/README
+++ b/README
@@ -1,8 +1,8 @@
-C++ wrapper for gtksourceview, version 3.2.0.
+C++ wrapper for gtksourceview, version 3.12.0.
 
 Current dependencies:
 - to build a library from tarball:
-  * gtksourceview >= 3.2.0
+  * gtksourceview >= 3.12.0
   * glibmm >= 2.28.0
   * gtkmm >= 3.2.0
 - to build a documentation: