Change gitter link to zulip for hub (#799)

Co-authored-by: Chris Holdgraf <[email protected]>

Author: willingc

about.html

@@ -105,7 +105,7 @@
   - name: Rollin Thomas
     photo: Rollin_Thomas.jpg
     linkedin: https://www.linkedin.com/in/rollin-thomas-507185b5/
-    personal: https://www.nersc.gov/about/nersc-staff/programming-environments-and-models/rollin-thomas/
+    personal: https://profiles.lbl.gov/20396-rollin-thomas
     gh_handle: rcthomas
     twitter_handle: r_c_thomas
   - name: Ayaz Salikhov

hub.md

@@ -71,6 +71,6 @@ Like all Project Jupyter efforts, JupyterHub is an
 open-source and community-driven project. We'd love for you
 to join our community and contribute code, time, comments, or appreciation.
 
-**[The JupyterHub Gitter Channel](https://gitter.im/jupyterhub/jupyterhub)**
+**[The JupyterHub Zulip Channel](https://jupyter.zulipchat.com/#narrow/channel/469744-jupyterhub)**
 is a place where the JupyterHub community discuses developments in the
 JupyterHub technology, as well as best-practices in deploying and debugging.