Update README.md

Author: montyly

program-analysis/echidna/README.md

@@ -13,4 +13,6 @@ To learn through live coding sessions, watch our [Fuzzing workshop](https://www.
 - [Frequently Asked Questions](./frequently_asked_questions.md): Responses to common questions about Echidna
 - [Exercises](exercises): Practical exercises to enhance your understanding
 
-Join the team on Slack at: https://slack.empirehacking.nyc/ #ethereum
+Join the team on Slack at: https://slack.empirehacking.nyc/ #ethereum.
+
+If you are looking for help to build fuzzing capabilities for your team, check out our [invariant development as a service](https://www.trailofbits.com/services/software-assurance/#blockchain-invariant-development).