docs: bump supported shading language version

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
diff --git a/docs/shading.html b/docs/shading.html
index 19e20b1..4015cdf 100644
--- a/docs/shading.html
+++ b/docs/shading.html
@@ -67,7 +67,7 @@
 <h2 id="support">GLSL Version</h2>
 
 <p>
-The GLSL compiler currently supports version 1.40 of the shading language.
+The GLSL compiler currently supports version 3.30 of the shading language.
 </p>
 
 <p>