[clang-tidy][NFC] Fix error in example code for modernize-use-scoped-lock's doc (llvm#159722)

Author: flovent

clang-tools-extra/docs/clang-tidy/checks/modernize/use-scoped-lock.rst

@@ -51,8 +51,8 @@ Multiple ``std::lock_guard`` declarations only emit warnings:
 
   std::mutex M1, M2;
   std::lock(M1, M2);
-  std::lock_guard Lock1(M, std::adopt_lock); // warning: use single 'std::scoped_lock' instead of multiple 'std::lock_guard'
-  std::lock_guard Lock2(M, std::adopt_lock); // note: additional 'std::lock_guard' declared here
+  std::lock_guard Lock1(M1, std::adopt_lock); // warning: use single 'std::scoped_lock' instead of multiple 'std::lock_guard'
+  std::lock_guard Lock2(M2, std::adopt_lock); // note: additional 'std::lock_guard' declared here
 
 
 Limitations