fix(docs): added comma in config example (#1860)

add comma in documentation

Author: kellergoech

docs/src/content/docs/tutorial/k-lib.mdx

@@ -228,7 +228,7 @@ local k = import "github.com/grafana/jsonnet-libs/ksonnet-util/kausal.libsonnet"
 +      port: 9090,
 +      name: "prometheus"
 +    }
-+  }
++  },
 
   local deployment = k.apps.v1.deployment,
   local container = k.core.v1.container,