Updated readme for 0.9.6.4

readme.txt

@@ -63,6 +63,12 @@ GLM is a header only library, there is nothing to build, just include it.
 More informations in GLM manual:
 http://glm.g-truc.net/glm.pdf
 
+================================================================================
+GLM 0.9.6.4: 2015-0X-XX
+--------------------------------------------------------------------------------
+Fixes:
+
+
 ================================================================================
 GLM 0.9.6.3: 2015-02-15
 --------------------------------------------------------------------------------