docs: fix slack link using never-expiring invitation

Author: mars-lan

README.md

@@ -1,7 +1,7 @@
 # DataHub: A Generalized Metadata Search & Discovery Tool
 [![Version](https://img.shields.io/github/v/release/linkedin/datahub?include_prereleases)](https://github.com/linkedin/datahub/releases)
 [![Build Status](https://travis-ci.org/linkedin/datahub.svg)](https://travis-ci.org/linkedin/datahub)
-[![Get on Slack](https://img.shields.io/badge/slack-join-orange.svg)](https://datahubspace.slack.com/join/shared_invite/zt-cl60ng6o-6odCh_I~ejZKE~a9GG30PA)
+[![Get on Slack](https://img.shields.io/badge/slack-join-orange.svg)](https://join.slack.com/t/datahubspace/shared_invite/zt-dkzbxfck-dzNl96vBzB06pJpbRwP6RA)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](https://github.com/linkedin/datahub/blob/master/CONTRIBUTING.md)
 [![License](https://img.shields.io/github/license/linkedin/datahub)](LICENSE)
 
@@ -24,7 +24,7 @@
 
 > :sparkles:Mar 2020 Update: 
 > - DataHub v0.3.1 has just been released. See [relase notes](https://github.com/linkedin/datahub/releases/tag/v0.3.1) for more details.
-> - We're on [Slack](https://datahubspace.slack.com/join/shared_invite/zt-cl60ng6o-6odCh_I~ejZKE~a9GG30PA) now! Ask questions and keep up with the latest announcement.
+> - We're on [Slack](https://join.slack.com/t/datahubspace/shared_invite/zt-dkzbxfck-dzNl96vBzB06pJpbRwP6RA) now! Ask questions and keep up with the latest announcement.
 
 ## Introduction
 DataHub is LinkedIn's generalized metadata search & discovery tool. To learn more about DataHub, check out our