website: Up supported clang version to 11

Change-Id: Ibeb5200a7919aa3fb38399305bf355805e603e69
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/48723
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby R. Bruce <bbruce@ucdavis.edu>
diff --git a/_pages/documentation/general_docs/building/index.md b/_pages/documentation/general_docs/building/index.md
index a8ccfc8..d4cebda 100644
--- a/_pages/documentation/general_docs/building/index.md
+++ b/_pages/documentation/general_docs/building/index.md
@@ -40,7 +40,7 @@
 * **gcc**: gcc is used to compiled gem5. **Version >=7 must be used**. We
 support up to gcc Version 10.
 * **Clang**: Clang can also be used. At present, we support Clang 6 to
-Clang 9 (inclusive).
+Clang 11 (inclusive).
 * **SCons** : gem5 uses SCons as its build environment. SCons 3.0 or greater
 must be used.
 * **Python 3.6+** : gem5 relies on Python development libraries. gem5 can be