Merge pull request #7060 from NomicFoundation/chore/add-warning-to-hardhat-utils

docs: add a warning to Hardhat utils indicating it is internal

Author: kanej

v-next/hardhat-utils/README.md

@@ -1,5 +1,7 @@
 # Hardhat utils
 
+> **Warning:** This package is **internal** to Hardhat, its **API is considered internal** and may change without notice i.e. we may push breaking changes in a `hardhat-utils` major version bump to support a patch change in Hardhat.
+
 This package contains utilities used by Hardhat 3 and its plugins.
 
 This package is internal to Hardhat and should not be used directly.