Add more environments to guestbook. Add README content

guestbook/environments/prod/params.libsonnet

@@ -0,0 +1,17 @@
+local params = std.extVar("__ksonnet/params");
+local globals = import "globals.libsonnet";
+local envParams = params + {
+  components +: {
+    // Insert component parameter overrides here. Ex:
+    // guestbook +: {
+    //   name: "guestbook-dev",
+    //   replicas: params.global.replicas,
+    // },
+  },
+};
+
+{
+  components: {
+    [x]: envParams.components[x] + globals, for x in std.objectFields(envParams.components)
+  },
+}