fix copy/paste error

Author: michaelrj-google

utils/bazel/llvm-project-overlay/libc/test/src/stdbit/BUILD.bazel

@@ -2,7 +2,7 @@
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-# Tests for LLVM libc stdio.h functions.
+# Tests for LLVM libc stdbit.h functions.
 
 load("//libc/test:libc_test_rules.bzl", "libc_test")