Fixed release note url. (#716)

Author: avas27JTG

plugin.json

@@ -4,7 +4,7 @@
     "description": "GitHub plugin for Mattermost.",
     "homepage_url": "https://github.com/mattermost/mattermost-plugin-github",
     "support_url": "https://github.com/mattermost/mattermost-plugin-github/issues",
-    "release_notes_url": "https://github.com/mattermost/mattermost-plugin-github/releases/tag/v2.1.6",
+    "release_notes_url": "https://github.com/mattermost/mattermost-plugin-github/releases/tag/v2.1.7",
     "icon_path": "assets/icon.svg",
     "version": "2.1.7",
     "min_server_version": "6.5.0",