Add mastodon link (#6432)

* List LinkedIn, YouTube, Twitter and Mastodon channels
* Update Email address

Co-authored-by: Reshama Shaikh <[email protected]>

Author: michaelosthege

README.rst

@@ -80,13 +80,20 @@ Please choose from the following:
 Contact
 =======
 
-We are using `discourse.pymc.io <https://discourse.pymc.io/>`__ as our main communication channel. You can also follow us on `Twitter @pymc_devs <https://twitter.com/pymc_devs>`__ for updates and other announcements.
+We are using `discourse.pymc.io <https://discourse.pymc.io/>`__ as our main communication channel.
 
 To ask a question regarding modeling or usage of PyMC we encourage posting to our Discourse forum under the `“Questions” Category <https://discourse.pymc.io/c/questions>`__. You can also suggest feature in the `“Development” Category <https://discourse.pymc.io/c/development>`__.
 
+You can also follow us on these social media platforms for updates and other announcements:
+
+- `LinkedIn @pymc <https://www.linkedin.com/company/pymc/>`__
+- `YouTube @PyMCDevelopers <https://www.youtube.com/c/PyMCDevelopers>`__
+- `Twitter @pymc_devs <https://twitter.com/pymc_devs>`__
+- `Mastodon @[email protected] <https://bayes.club/@pymc>`__
+
 To report an issue with PyMC please use the `issue tracker <https://github.com/pymc-devs/pymc/issues>`__.
 
-Finally, if you need to get in touch for non-technical information about the project, `send us an e-mail <pymc.devs@gmail.com>`__.
+Finally, if you need to get in touch for non-technical information about the project, `send us an e-mail <info@pymc-devs.org>`__.
 
 License
 =======