docs: add tip for pinning tool version in README.md

Author: shenxianpeng

README.md

@@ -72,6 +72,9 @@ repos:
         args: [--checks=.clang-tidy, --version=21] # Specifies version
 ```
 
+> [!TIP]
+> For production use, always pin the tool version explicitly with `--version` (e.g. `--version=21`) so upgrades to `cpp-linter-hooks` never silently change your linter version.
+
 ## Output
 
 ### clang-format Output