Add more manifest metadata (#86)

Author: hanzei

plugin.json

@@ -2,6 +2,8 @@
   "id": "mattermost-autolink",
   "name": "Autolink",
   "description": "Automatically rewrite text matching a regular expression into a Markdown link.",
+  "homepage_url": "https://github.com/mattermost/mattermost-plugin-autolink",
+  "support_url": "https://github.com/mattermost/mattermost-plugin-autolink/issues",
   "version": "1.1.2",
   "min_server_version": "5.16.0",
   "server": {