chore: switch chat links to slack (#2782)

website/data/landing.yaml

@@ -34,7 +34,7 @@ community:
     - feature: "Built on the JAMstack"
       description: "Netlify CMS is based on client-side JavaScript, reusable APIs and prebuilt Markup. Compared to server-side CMS like WordPress, this means better performance, higher security, lower cost of scaling, and a better developer experience. You can learn more about the JAMstack on [jamstack.org](https://jamstack.org)."
     - feature: "Support when you need it"
-      description: "Get up and running with comprehensive [documentation](/docs) and templates or work through difficult problems with help from the community on [Gitter](https://gitter.im/netlify/NetlifyCMS)."
+      description: "Get up and running with comprehensive [documentation](/docs) and templates or work through difficult problems in our [community chat](https://netlifycms.org/chat)."
     - feature: "A community-driven project you can help evolve"
       description: "Netlify CMS is built by a community of more than 100 contributors — and you can help. Join our [bi-weekly planning sessions](/community) or read the [contributing guide](/docs/contributor-guide) to join in."
   contributors: "Made possible by awesome contributors"

website/data/notifications.yml

@@ -9,11 +9,11 @@ notifications:
       https://www.eventbrite.com/e/netlify-cms-planning-session-bi-weekly-tickets-35794058994
   - loud: true
     message: >-
-      We have a community on Gitter - join now to ask questions and discuss the
+      We have a community chat - join now to ask questions and discuss the
       project with other devs!
     published: false
-    title: Gitter shoutout
-    url: 'https://gitter.im/netlify/netlifycms'
+    title: Chat shoutout
+    url: 'https://netlifycms.org/chat'
   - loud: true
     message: Netlify CMS now supports GitLab!
     published: false