Add various manifest fields

CloudronManifest.json

@@ -1,12 +1,22 @@
 {
   "version": "0.1.0",
   "id": "io.prometheus.cloudronapp",
+  "title": "Prometheus",
   "author": "Erik Tadevosyan",
-  "healthCheckPath": "/status",
+  "description": "file://DESCRIPTION.md",
+  "tagline": "From metrics to insight",
+  "healthCheckPath": "/",
   "httpPort": 9090,
   "icon": "logo.png",
   "addons": {
     "localstorage": {}
   },
-  "manifestVersion": 2
+  "manifestVersion": 2,
+  "website": "https://prometheus.io/",
+  "contactEmail": "support@cloudron.io",
+  "tags": [ "metrics", "analytics", "graphite", "collect", "graphs" ],
+  "changelog": "file://CHANGELOG",
+  "documentationUrl": "https://docs.cloudron.io/apps/prometheus/",
+  "minBoxVersion": "5.5.0",
+  "forumUrl": "https://forum.cloudron.io/category/112/prometheus"
 }

DESCRIPTION.md

@@ -0,0 +1,19 @@
+This app packages Prometheus <upstream>2.22.0</upstream>
+
+Prometheus, a Cloud Native Computing Foundation project, is a systems and service monitoring system.
+It collects metrics from configured targets at given intervals, evaluates rule expressions, displays
+the results, and can trigger alerts when specified conditions are observed.
+
+## Features
+
+The features that distinguish Prometheus from other metrics and monitoring systems are:
+
+* A multi-dimensional data model (time series defined by metric name and set of key/value dimensions)
+* PromQL, a powerful and flexible query language to leverage this dimensionality
+* No dependency on distributed storage; single server nodes are autonomous
+* An HTTP pull model for time series collection
+* Pushing time series is supported via an intermediary gateway for batch jobs
+* Targets are discovered via service discovery or static configuration
+* Multiple modes of graphing and dashboarding support
+* Support for hierarchical and horizontal federation
+