message: Fix broken Slack link in Quic github readme file
  Summary: as title
diff: @@ -119,7 +119,7 @@ We'd love to have your help in making `mvfst` better. If you're interested, plea
  read our guide to [guide to contributing](CONTRIBUTING.md)
  Please also join our
  -[slack](https://join.slack.com/t/mvfst/shared_invite/enQtNjE0ODIwNDU3MDU4LWFkOTc0ZTQ4NzczZmE2MjRlMjQxNWQxNDAyYzAzMDQ5MTQ0ZGI0YTJhZWM0MThhM2FiYzc0Zjg3MTYyNDg2MWI) to ask questions or start discussions.
  +[slack](https://mvfst.slack.com) to ask questions or start discussions.
  ## License
  `mvfst` is MIT licensed, as found in the LICENSE file.
  