domain docs: hosts (#628)

website/content/docs/concepts/domain-model/hosts.mdx

@@ -12,9 +12,8 @@ A host is a resource
 that represents a computing element with a network address
 reachable from Boundary.
 A host belongs to a [host catalog][].
-A host can only be included
-by [host sets][]
-from the same host catalog as the host.
+Hosts can only be associated with [host sets][] 
+from the same host catalog as the host. 
 
 ## Attributes