Add challengeHound to README (#932)

Signed-off-by: Will Hunt <[email protected]>

Author: Half-Shot

README.md

@@ -16,6 +16,7 @@ A Matrix bot for connecting to external services like GitHub, GitLab, JIRA, and
 
 We richly support the following integrations:
 
+- [Challenge Hound](https://matrix-org.github.io/matrix-hookshot/latest/setup/challengehound.html)
 - [Figma](https://matrix-org.github.io/matrix-hookshot/latest/setup/figma.html)
 - [Generic Webhooks](https://matrix-org.github.io/matrix-hookshot/latest/setup/webhooks.html)
 - [GitHub](https://matrix-org.github.io/matrix-hookshot/latest/setup/github.html)