fix: specified cpp for code block in README.md

README.md

@@ -25,13 +25,13 @@ Either `git clone --recursive` or remember to `git submodule update --init --rec
 > (1) Bracket exceptions:
 > * using scoped_lock in arbitrary blocks, prefer tailed lisp brackets
 
-```
+```cpp
 struct Data {
     int x{ 0 }, y{ 0 };
 };
 void MyFunction(Data const &data) { // K&R here
     DoAsynchronousThings();
-    { scoped_lock lock{ myMutex };
+    { std::scoped_lock lock{ myMutex };
         myVariable++;
     } // not quite lisp, lisp with a tail
     DoMoreAsynchronousThings();