✨ Add Mettermost Alerting

example/docker-compose-mattermost/config.yaml

@@ -0,0 +1,6 @@
+services:
+  - name: example
+    url: http://example.org
+    interval: 30s
+    conditions:
+      - "[STATUS] == 200"

example/docker-compose-mattermost/docker-compose.yml

@@ -0,0 +1,13 @@
+version: "3.8"
+services:
+    gatus:
+        image: twinproduction/gatus:latest
+        ports:
+          - 8080:8080
+        volumes:
+          - ./config.yaml:/config/config.yaml
+
+    mattermost-preview:
+        image: mattermost/mattermost-preview:latest
+        ports:
+          - 8065:8065