Updated readme.txt for GLM 0.9.0.8

readme.txt

@@ -13,6 +13,12 @@ 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-manual.pdf
 
+================================================================================
+GLM 0.9.0.8: 2011-02-13
+--------------------------------------------------------------------------------
+- Added quaternion product operator.
+- Clarify that GLM is a header only library.
+
 ================================================================================
 GLM 0.9.0.7: 2011-01-30
 --------------------------------------------------------------------------------