docs: change link to the CZI science community Slack (#2662)

README.md

@@ -58,7 +58,7 @@ Please [file an issue](https://github.com/chanzuckerberg/cellxgene/issues/new/ch
 ### Finding help
 
 We'd love to hear from you!
-For questions, suggestions, or accolades, [join the `#cellxgene-users` channel on the CZI Science Slack](https://join-cellxgene-users.herokuapp.com/) and say "hi!".
+For questions, suggestions, or accolades, join the `#cellxgene-users` channel on the [CZI Science Community Slack](https://czi.co/science-slack) and say "hi!".
 
 For any errors, [report bugs on Github](https://github.com/chanzuckerberg/cellxgene/issues).
 

client/src/components/leftSidebar/infoMenu.js

@@ -16,7 +16,7 @@ const InformationMenu = React.memo((props) => {
             rel="noopener"
           />
           <MenuItem
-            href="https://join-cellxgene-users.herokuapp.com/"
+            href="https://czi.co/science-slack"
             target="_blank"
             icon="chat"
             text="Chat"