Feat(docs): add test-keys script to validate Onion Service keys candidates

README.md

@@ -181,6 +181,17 @@ correlated. This means that if an attacker takes control of a backend instance t
 uses a keypair generated in the same pool, then the attacker can try to regenerate
 related keys.
 
+### Testing your candidate keypairs
+
+Once you selected a candidate address that suits your needs, you might want to
+test if the keys are validated by the Tor process, just to make sure.
+
+Onionmine provides a test script for that, located at `bin/test-keys`.
+
+Check [this
+issue](https://gitlab.torproject.org/tpo/onion-services/onionmine/-/issues/2)
+to see how it works.
+
 ### HARICA X.509 certificates compatibility
 
 Onionmine ships with [onion-csr](https://gitlab.torproject.org/tpo/onion-services/onionmine/-/issues/17) as a submodule