Deprecate native P&T, focus Composition docs on functions

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

content/master/concepts/_index.md

@@ -55,16 +55,6 @@ building and managing external resources through Kubernetes.
   Composite Resource. Platform users create Claims in their unique namespace,
   isolating their resources from other teams in other namespaces. 
 
-* [**Composition Functions**]({{<ref "./composition-functions">}}) are custom
-  programs, written your programming language of choice, to apply logic and
-  loops before or after Crossplane creates resources. 
-
-* [**Patches and Transforms**]({{<ref "./patch-and-transform">}}) allow platform
-  engineers to use user inputs to their custom API and change how Crossplane
-  creates resources. Patches and transforms allow for flexible and
-  abstract inputs like `big` or `encrypted` to have specific meanings when
-  creating the actual managed resources.
-
 * [**EnvironmentConfigs**]({{<ref "./environment-configs">}}) are an in-memory
   data store, like a Kubernetes ConfigMap. EnvironmentConfigs are useful for
   custom resource mapping or storing and retrieving data across Claims and

content/master/concepts/composite-resources.md

@@ -133,16 +133,27 @@ kind: Composition
 metadata:
   name: my-composition
 spec:
-  resources:
-    - name: database
-      base:
-        # Removed for brevity
-      patches:
-      - fromFieldPath: metadata.annotations
-        toFieldPath: metadata.annotations
+  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 patching resources refer to the [Patch and Transform]({{<ref "./patch-and-transform">}}) documentation. 
+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