Merge #1228

1228: Enable sponsorship through FUNDING.yml r=mergify[bot] a=muhlemmer

## What type of PR?

Documentation

## What does this PR do?

Add FUNDING.yml for sponsorship button on top of github page. (Will become active after this is merged). And update the FAQ section to reflect this addition.

### Related issue(s)

Related (but long-closed): #508

## Prerequistes
Before we can consider review and merge, please make sure the following list is done and checked.
If an entry in not applicable, you can check it or remove it from the list.

- [x] In case of feature or enhancement: documentation updated accordingly
- [x] Unless it's docs or a minor change: add [changelog](https://mailu.io/master/contributors/guide.html#changelog) entry file.


Co-authored-by: Tim Möhlmann <muhlemmer@gmail.com>

.github/FUNDING.yml

@@ -0,0 +1,4 @@
+community_bridge: mailu
+
+# Will be done once contributors pass the wait list.
+#github: # Replace with up to 4 GitHub Sponsors-enabled usernames e.g., [user1, user2]

docs/faq.rst

@@ -71,15 +71,28 @@ We thank you for your understanding and patience.
 I would like to donate (for a feature)
 ``````````````````````````````````````
 
-Donations are welcome to the authors of the project directly, we do not manage any central
-donation pot. Also, check the ``AUTHORS.md`` file for Patreon link or equivalent. If you
-wish to contact a contributor specifically, please do so on `Matrix`_
+We maintain a `Communtity Bridge`_ project through which you can donate.
+This budget will be used to pay for development of features, mentorship and hopefully future events.
+Contributing companies or individuals can be paid from this budget to support their development efforts.
+
+We are also looking into GitHub's integrated sponorship program for individual contributors.
+Once those become available, we will add them to the project.
+
+Please click the |sponsor| button on top of our GitHub Page for current possibilities.
+
+.. |sponsor| image:: assets/sponsor-button.png
+  :height: 1.2em
+  :alt: sponsor
+  :target: `GitHub`_
+
 
 .. _`Matrix`: https://matrix.to/#/#mailu:tedomum.net
 .. _`open issues`: https://github.com/Mailu/Mailu/issues
 .. _`new issue`: https://github.com/Mailu/Mailu/issues/new
 .. _`Enhancement issues`: https://github.com/Mailu/Mailu/issues?q=is%3Aissue+is%3Aopen+label%3Atype%2Fenhancement
 .. _`Feature request issues`: https://github.com/Mailu/Mailu/issues?q=is%3Aopen+is%3Aissue+label%3Atype%2Ffeature
+.. _`GitHub`: https://github.com/Mailu/Mailu
+.. _`Communtity Bridge`: https://funding.communitybridge.org/projects/mailu
 
 Deployment related
 ------------------

towncrier/newsfragments/508.misc

@@ -0,0 +1 @@
+Enable sponsorship