[llvm] [Docs] Fix the description about %clang_cpp (PR #152842)

[via llvm-commits]

https://github.com/parabola94 updated https://github.com/llvm/llvm-project/pull/152842

>From f646c129059361739778d6b301807e13c93851e3 Mon Sep 17 00:00:00 2001
From: parabola94 <heavybaby5000 at toki.waseda.jp>
Date: Sat, 9 Aug 2025 16:30:55 +0900
Subject: [PATCH] [Docs] Fix the description about %clang_cpp

---
 llvm/docs/TestingGuide.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/docs/TestingGuide.rst b/llvm/docs/TestingGuide.rst
index b1819c795bab4..f79d7eacd5b6c 100644
--- a/llvm/docs/TestingGuide.rst
+++ b/llvm/docs/TestingGuide.rst
@@ -834,7 +834,7 @@ Besides replacing LLVM tool names, the following substitutions are performed in
    Invokes the Clang driver.
 
 ``%clang_cpp``
-   Invokes the Clang driver for C++.
+   Invokes the Clang driver as the preprocessor.
 
 ``%clang_cl``
    Invokes the CL-compatible Clang driver.