Updated copyright dates

doc/src/data.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 
-<glm copyright="Copyright © 2005 - 2010 ">
+<glm copyright="Copyright © 2005 - 2011 ">
   <downloads>
     <section name="GLM - zip files">
       <download name="GLM 0.9.0.6" date="21/12/2010" size="2.2 MB" link="https://sourceforge.net/projects/ogl-math/files/glm-0.9.0.6/glm-0.9.0.6.zip/download"/>