Adding metadata for the upbound marketplace (#20)

Fixes: #19
cc: @luebken

package/crossplane.yaml

@@ -2,3 +2,19 @@ apiVersion: meta.pkg.crossplane.io/v1
 kind: Provider
 metadata:
   name: provider-github
+  annotations:
+    meta.crossplane.io/maintainer: Coop Norge SA
+    meta.crossplane.io/source: https://github.com/coopnorge/provider-github
+    meta.crossplane.io/license: Apache-2.0
+    meta.crossplane.io/description: |
+      The Github Crossplane provider adds support for 
+      managing Github resources in kubernetes.
+
+    meta.crossplane.io/readme: |
+      `provider-github` is a crossplane infrastructure provider for 
+      [Github](https://github.com). 
+
+      It is based on the Terraform Github provider. Read the 
+      [readme](https://github.com/coopnorge/provider-github/blob/main/README.md)
+      for instructions.
+