[libcxx-commits] [libcxx] [libcxx] Update testing documentation about CI container images. (PR #149192)

[Aiden Grossman via libcxx-commits]

================
@@ -261,6 +265,71 @@ GCC, and CMake.
 .. note:: This image is pulled from Docker hub and not rebuild when changing
    the Dockerfile.
 
+Updating the CI testing container images
+----------------------------------------
+
+The libcxx linux premerge testing can run on one of three sets of runner
+groups. The three runner group names are "llvm-premerge-libcxx-runners",
+"llvm-premerge-libcxx-release-runners" or "llvm-premerge-libcxx-next-runners".
----------------
boomanaiden154 wrote:

Nit: or->and

https://github.com/llvm/llvm-project/pull/149192