Update GitHub issues submission and README.md to reference GitHub Discussion (and not zulip) (#717)

This PR updates the issue and README.md to use Github Diiscussions (no
longer using zulip... or we only check it intermittently).

See comment
#688 (comment).

Author: jtaala

.github/ISSUE_TEMPLATE/config.yml

@@ -1,5 +1,5 @@
 blank_issues_enabled: true
 contact_links:
-  - name: Zulip Chat
-    url: https://paperwm.zulipchat.com/
-    about: Talk to us on Zulip.
+  - name: PaperWM Discussions
+    url: https://github.com/paperwm/PaperWM/discussions/
+    about: Ask a question or start a discussion on PaperWM.

README.md

@@ -4,7 +4,7 @@
 > 
 > ### If you're using Gnome 42-44, please install via [extensions.gnome.org](https://extensions.gnome.org/extension/6099/paperwm/) OR use the [`gnome-44`](https://github.com/paperwm/PaperWM/tree/gnome-44) branch (see the [Installation](#installation) section for more information).
 
-[![project chat](https://img.shields.io/badge/zulip-join_chat-brightgreen.svg)](https://paperwm.zulipchat.com)
+[![project chat](https://img.shields.io/badge/PaperWM_Discussions-join_chat-brightgreen)](https://github.com/paperwm/PaperWM/discussions)
 
 PaperWM is a [Gnome Shell](https://wiki.gnome.org/Projects/GnomeShell) extension which provides scrollable tiling of windows and per monitor workspaces. It's inspired by paper notebooks and tiling window managers.
 
@@ -14,7 +14,7 @@ _While PaperWM can be installed on a wide range of Gnome versions, new features
 
 While technically an [extension](https://wiki.gnome.org/Projects/GnomeShell/Extensions) it's to a large extent built on top of the Gnome desktop rather than merely extending it.
 
-We often hang out on [zulip](https://paperwm.zulipchat.com).
+Have questions or comments?  Please ask on our [Github Discussions](https://github.com/paperwm/PaperWM/discussions) board.
 
 ## Installation