Update link for slack invite

doc/help.rst

@@ -7,6 +7,6 @@ If you have questions about Glue, we'd love to hear from you. There are several
 
 * Ask us on `Twitter <https://twitter.com/glueviz>`_.
 * Post a question on the `Glue mailing list <https://groups.google.com/forum/#!forum/glue-viz>`_.
-* Join the `Slack channel <https://glueviz.slack.com>`_ - note that you will need to first get an account `here <https://glueviz-slack-invite.herokuapp.com>`_
+* Join the `Slack channel <https://glueviz.slack.com>`_ - note that you will need to first get an account `here <https://join.slack.com/t/glueviz/shared_invite/zt-1p5amn7ee-wTZCJJNlgxCTRup3SrSh3g>`_
 * For specific bug reports, open a new issue on the `GitHub page <https://github.com/glue-viz/glue/issues>`_.
 * Send feedback from Glue itself by selecting ``Send Feedback`` from the help menu.

doc/index.rst

@@ -53,7 +53,7 @@ Glue application to the more advanced ways of interacting with Glue from Python.
 .. note:: For any questions or help with using glue, you can always join the
           `user support mailing list <https://groups.google.com/forum/#!forum/glue-viz>`_
           or ask questions on `Slack <https://glueviz.slack.com>`_
-          (note that you will need to sign up for an account `here <https://glueviz-slack-invite.herokuapp.com>`_).
+          (note that you will need to sign up for an account `here <https://join.slack.com/t/glueviz/shared_invite/zt-1p5amn7ee-wTZCJJNlgxCTRup3SrSh3g>`_).
 
 Using the Glue application
 --------------------------

doc/whatsnew/whatsnew.rst

@@ -688,7 +688,7 @@ New Slack community
 
 We have now set up Slack for any glue help/discussions, and we encourage you to
 sign up! You will need to first get an account `here
-<https://glueviz-slack-invite.herokuapp.com>`_ after which you will be able to
+<https://join.slack.com/t/glueviz/shared_invite/zt-1p5amn7ee-wTZCJJNlgxCTRup3SrSh3g>`_ after which you will be able to
 sign in to https://glueviz.slack.com.
 
 Improved interface