Move gitops toolkit index under components/

Signed-off-by: Michael Bridgen <michael@weave.works>

docs/components/index.md

@@ -0,0 +1,26 @@
+# GitOps Toolkit components
+
+The GitOps Toolkit is the set of APIs and controllers that make up the
+runtime for Flux v2. The APIs comprise Kubernetes custom resources,
+which can be created and updated by a cluster user, or by other
+automation tooling.
+
+You can use the toolkit to extend Flux, and to build your own systems
+for continuous delivery. The [the source-watcher
+guide](../dev-guides/source-watcher/) is a good place to start.
+
+A reference for each component and API type is linked below.
+
+- [Source Controller](source/controller.md)
+    - [GitRepository CRD](source/gitrepositories.md)
+    - [HelmRepository CRD](source/helmrepositories.md)
+    - [HelmChart CRD](source/helmcharts.md)
+    - [Bucket CRD](source/buckets.md)
+- [Kustomize Controller](kustomize/controller.md)
+    - [Kustomization CRD](kustomize/kustomization.md)
+- [Helm Controller](helm/controller.md)
+    - [HelmRelease CRD](helm/helmreleases.md)
+- [Notification Controller](notification/controller.md)
+    - [Provider CRD](notification/provider.md)
+    - [Alert CRD](notification/alert.md)
+    - [Receiver CRD](notification/receiver.md)