Document how to run the acceptance tests as an errand on cf-deployment

- we had something like this in our private deployments repo, but there
wasn't anything in the open source

[#151422470]

jobs/acceptance_tests/README.md

@@ -0,0 +1,35 @@
+To run the acceptance tests as an errand, apply the following ops-file to your `cf-deployment`:
+
+```yaml
+---
+- type: replace
+  path: /instance_groups/name=routing_acceptance_tests?
+  value:
+    name: routing_acceptance_tests
+    lifecycle: errand
+    azs:
+    - z1
+    instances: 1
+    vm_type: minimal
+    stemcell: default
+    networks:
+    - name: default
+    jobs:
+    - name: acceptance_tests
+    release: routing
+    properties:
+      tcp_emitter:
+        oauth_secret: "((uaa_clients_tcp_emitter_secret))"
+      acceptance_tests:
+        nodes: 1
+        addresses: [10.244.0.137] # replace this with the IP address of your TCP router
+        cloud_controller:
+          api: "api.((system_domain))"
+          admin_user: "admin"
+          admin_password: "((cf_admin_password))"
+          apps_domain: "((system_domain))"
+          use_http: true
+        system_domain: "((system_domain))"
+        skip_ssl_validation: true
+        include_http_routes: true
+```