Added ntfy and Zulip (#4694) documentation.

docs/docs/messaging/index.md

@@ -8,6 +8,8 @@
 [XMPP Setup](#xmpp-setup)  
 [CallMeBot Setup](#callmebot-setup)  
 [Pushover Setup](#pushover-setup)  
+[ntfy Setup](#ntfy-setup)  
+[Zulip Setup](#zulip-setup)  
 [User Setup](#user-setup)  
 [Administrator Management](#administrator-management)  
 [Two-Factor Authentication](#two-factor-authentication)  
@@ -160,6 +162,35 @@ Once setup, the server will offer users the "Pushover" option when setting up me
 
 ![](images/MC2-Pushover1.png)
 
+## ntfy setup
+
+[ntfy](https://ntfy.sh/) is a completely free notification service. You can enable the ntfy integration with the following config.json section:
+
+```json
+{
+  "messaging": {
+    "ntfy": true
+  }
+}
+```
+
+No setup is reqired to enable this. When using ntfy, make sure you use a suffisently random topic name so that others can't guess the name and subscribe to it to receive your messages.
+
+![](images/MC2-Ntfy1.png)
+
+## Zulip setup
+
+You can enable the MeshCentral [Zulip](https://zulip.com/) integration with the following config.json section:
+
+```json
+{
+  "messaging": {
+    email: "your-bot@zulip.com",
+    api_key: "your_32_character_api_key"
+  }
+}
+```
+
 ## User Setup
 
 Once one or more messaging systems are setup with MeshCentral, users will be able to register their handle and verify that they own that account by typing in a 6 digit code.