[clang-tidy] Fix example in documentation, NFC

[krasimir]

Summary

A fix in documentation.

[bkramer]

fun fun fun fun fun

docs/clang-tidy/checks/modernize-replace-random-shuffle.rst

 .. code-block:: c++
 
   std::vector<int> v;
 
   // First example
   std::random_shuffle(vec.begin(), vec.end());
 
   // Second example
-  std::random_shuffle(vec.begin(), vec.end(), randomFun);
+  std::random_shuffle(vec.begin(), vec.end(), randomFunc);
 
 Both of these examples will be replaced with:
 
 .. code-block:: c++
 
   std::shuffle(vec.begin(), vec.end(), std::mt19937(std::random_device()()));
 
 The second example will also receive a warning that ``randomFunc`` is no longer supported in the same way as before so if the user wants the same functionality, the user will need to change the implementation of the ``randomFunc``.
 
 One thing to be aware of here is that ``std::random_device`` is quite expensive to initialize. So if you are using the code in a performance critical place, you probably want to initialize it elsewhere.