Drop docs on naming resources with external name annotation

It's an MR feature, not a composition feature. It's documented in the MR
docs.

Signed-off-by: Nic Cope <nicc@rk0n.org>

content/v2.0-preview/composition/composite-resources.md

@@ -85,75 +85,6 @@ NAME                    SYNCED   READY   COMPOSITION         AGE
 my-composite-resource   True     True    my-composition      4s
 ```
 
-### Naming external resources
-By default, managed resources created by a composite resource have the name of
-the composite resource, followed by a random suffix.
-
-<!-- vale Google.FirstPerson = NO -->
-<!-- vale Crossplane.Spelling = NO -->
-For example, a composite resource named "my-composite-resource" creates external
-resources named "my-composite-resource-fqvkw." 
-<!-- vale Google.FirstPerson = YES -->
-<!-- vale Crossplane.Spelling = YES  -->
-
-Resource names can be deterministic by applying an 
-{{<hover label="annotation" line="5">}}annotation{{</hover>}} to the composite
-resource. 
-
-```yaml {label="annotation",copy-lines="none"}
-apiVersion: example.org/v1alpha1
-kind: MyDatabase
-metadata:
-  namespace: default
-  name: my-composite-resource
-  annotations: 
-    crossplane.io/external-name: my-custom-name
-# Removed for brevity
-```
-
-Inside the Composition, use a 
-{{<hover label="comp" line="10">}}patch{{</hover>}}
-to apply the external-name to the resources. 
-
-The {{<hover label="comp" line="11">}}fromFieldPath{{</hover>}} patch copies the
-{{<hover label="comp" line="11">}}metadata.annotations{{</hover>}} field from
-the composite resource to the 
-{{<hover label="comp" line="12">}}metadata.annotations{{</hover>}} inside the
-managed resource. 
-
-{{<hint "note" >}}
-If a managed resource has the `crossplane.io/external-name` annotation
-Crossplane uses the annotation value to name the external resource.
-{{</hint >}}
-
-```yaml {label="comp",copy-lines="none"}
-apiVersion: apiextensions.crossplane.io/v1
-kind: Composition
-metadata:
-  name: my-composition
-spec:
-  mode: Pipeline
-  pipeline:
-  - step: patch-and-transform
-    functionRef:
-      name: function-patch-and-transform
-    input:
-      apiVersion: pt.fn.crossplane.io/v1beta1
-      kind: Resources
-      resources:
-      - name: database
-        base:
-          # Removed for brevity
-        patches:
-        - fromFieldPath: metadata.annotations
-          toFieldPath: metadata.annotations
-```
-
-For more information on using `function-patch-and-transform` to patch
-resources refer to the
-[Function Patch and Transform]({{<ref "../guides/function-patch-and-transform">}})
-documentation. 
-
 ### Composition selection
 
 Select a specific Composition for a composite resource to use with