Docs: Added redirect entries for multicast plugin and the cloud plugins

docs/plugins/index.asciidoc

@@ -67,3 +67,6 @@ include::integrations.asciidoc[]
 
 include::authors.asciidoc[]
 
+include::redirects.asciidoc[]
+
+

docs/plugins/redirects.asciidoc

@@ -0,0 +1,40 @@
+["appendix",role="exclude",id="redirects"]
+= Deleted pages
+
+The following pages have moved or been deleted.
+
+[role="exclude",id="discovery-multicast"]
+=== Multicast Discovery Plugin
+
+The `multicast-discovery` plugin has been removed.  Instead, configure networking
+using unicast (see {ref}/modules-network.html[Network settings]) or using
+one of the <<discovery,cloud discovery plugins>>.
+
+[role="exclude",id="cloud-aws"]
+=== AWS Cloud Plugin
+
+The `cloud-aws` plugin has been split into two separate plugins:
+
+*  <<discovery-ec2>> (`discovery-ec2`)
+*  <<repository-s3>> (`repository-s3`)
+
+
+[role="exclude",id="cloud-azure"]
+=== Azure Cloud Plugin
+
+The `cloud-azure` plugin has been split into two separate plugins:
+
+*  <<discovery-azure>> (`discovery-azure`)
+*  <<repository-azure>> (`repository-azure`)
+
+
+[role="exclude",id="cloud-gce"]
+=== GCE Cloud Plugin
+
+The `cloud-gce` plugin has been renamed to <<discovery-gce>> (`discovery-gce`).
+
+
+
+
+
+