v3(docs): Add service route bindings to upgrade guide

[#175559041](https://www.pivotaltracker.com/story/show/175559041)

Author: pivotal-marcela-campo

docs/v3/source/includes/experimental_resources/service_route_bindings/_header.md

@@ -1,3 +1,3 @@
-## Service Route Binding (experimental)
+## Service Route Binding
 
 An instantiation of a service route binding.

docs/v3/source/includes/upgrade_guide/changed_resources/_service_instance_routes_in_v3.md

@@ -0,0 +1,14 @@
+### Service Instance routes in V3
+
+There is a new resource `service route binding` that represents a binding between a route and a service instance.
+
+Creation/Deletion of bindings is therefore done via that endpoint in v3.
+
+Audit events for route bindings have changed as follows:
+
+|**V2**|**V3**|
+|---|---|
+audit.service_instance.bind_route | audit.service_route_binding.start_create (async only)<br>audit.service_route_binding.create |
+audit.service_instance.unbind_route |audit.service_route_binding.start_delete (async only)<br>audit.service_route_binding.delete |
+
+Read more about the [service route binding resource](#service-route-binding).

docs/v3/source/includes/upgrade_guide/new_resources/_service_route_bindings.md

@@ -0,0 +1,11 @@
+### Service Route Bindings
+
+There is a new resource `service route binding` that represents a binding between a route and a service instance.a
+
+Creation/Deletion of bindings is therefore done via that endpoint in v3.
+
+This resource also supports metadata both in create and update requests.
+
+It has a nested resource for fetching binding parameters from the broker. Parameters are only set during creation.
+
+Read more about the [service route binding resource](#service-route-binding).

docs/v3/source/index.html.md

@@ -408,6 +408,7 @@ includes:
   - upgrade_guide/new_resources/isolation_segments
   - upgrade_guide/new_resources/manifests
   - upgrade_guide/new_resources/revisions
+  - upgrade_guide/new_resources/service_route_bindings.md
   - upgrade_guide/new_resources/sidecars
   - upgrade_guide/new_resources/tasks
   - upgrade_guide/changed_resources/header
@@ -417,6 +418,7 @@ includes:
   - upgrade_guide/changed_resources/routes_in_v3
   - upgrade_guide/changed_resources/security_groups_in_v3
   - upgrade_guide/changed_resources/service_brokers_in_v3
+  - upgrade_guide/changed_resources/service_instance_routes_in_v3
   - upgrade_guide/changed_resources/service_offerings_in_v3
   - upgrade_guide/changed_resources/service_plans_in_v3
   - upgrade_guide/changed_resources/service_plan_visibility_in_v3