add mention about potential false positives

Author: vbvictor

clang-tools-extra/docs/clang-tidy/Contributing.rst

@@ -675,6 +675,9 @@ Here's useful command to check your staged changes:
       -j $(nproc) -path build/ -p1 -only-check-in-db
   $ git clang-format
 
+Note that some warnings may be false positives or require careful consideration
+before fixing. Use your judgment and feel free to discuss in the pull request
+if you're unsure about a particular warning.
 
 Out-of-tree check plugins
 -------------------------