docs: add HAL docs for pacticipant-branch

lib/pact_broker/doc/views/index/pacticipant-branch.markdown

@@ -0,0 +1,25 @@
+# Pacticipant branch
+
+Allowed methods: `GET`, `DELETE`
+
+Path: `/pacticipants/{pacticipant}/branches/{branch}`
+
+Get or delete a pacticipant branch.
+
+## Create
+
+Branches cannot be created via the resource URL. They are created automatically when publishing contracts.
+
+## Get
+
+### Example
+
+    curl http://broker/pacticipants/Bar/branches/main -H "Accept: application/hal+json"
+
+## Delete
+
+Deletes a pacticipant branch. Does NOT delete the associated pacticipant versions.
+
+Send a `DELETE` request to the branch resource.
+
+    curl -XDELETE http://broker/pacticipants/Bar/branches/main

spec/lib/pact_broker/doc/coverage_spec.rb

@@ -3,6 +3,8 @@
 RSpec.describe "the HAL docs for the index" do
 
   let(:app) do
+    require "pact_broker/api"
+
     Rack::Builder.new do
       map "/docs" do
         run PactBroker::Doc::Controllers::App