.gitignore: ignore version doc files

.gitignore

@@ -28,6 +28,8 @@ starpu.log
 /tests/datawizard/data_lookup
 /doc/stamp-vti
 /doc/chapters/version.texi
+/doc/doxygen/chapters/version.sty
+/doc/doxygen/chapters/version.html
 /examples/basic_examples/block
 /examples/basic_examples/hello_world
 /examples/basic_examples/mult