docs: Add intro page to user docs

Author: jimmidyson

README.md

@@ -3,7 +3,9 @@
  SPDX-License-Identifier: Apache-2.0
  -->
 
-# CAPI Runtime Extensions Server
+# CAPI Runtime Extensions
+
+For user docs, please see [https://d2iq-labs.github.io/capi-runtime-extensions/].
 
 See [upstream documentation](https://cluster-api.sigs.k8s.io/tasks/experimental-features/runtime-sdk/index.html).
 

devbox.json

@@ -39,7 +39,7 @@
   "shell": {
     "scripts": {
       "preview-docs": [
-        "cd docs && hugo serve -F -D"
+        "cd docs && hugo server -F -D"
       ]
     }
   }

docs/content/_index.md

@@ -14,3 +14,26 @@ type = "docs"
   [cascade._target]
   path = "/**"
 +++
+
+Cluster API provides declarative APIs for provisioning, upgrading, and operating Kubernetes clusters across multiple
+infrastructure providers. The [`ClusterClass`][clusterclass] feature brings huge improvements in how users manage
+clusters, providing a single resource for a user to mutate to orchestrate upgrades, etc. `ClusterClass` also brings much
+improved templating over the [`clusterctl generate cluster`][clusterctl generate cluster] environment-variable driven
+templating by introducing variables specified with an OpenAPI schema that can then be applied to the generated resources
+via patches.
+
+The [Runtime SDK] feature provides an extensibility mechanism to hook into `ClusterClass` managed Kubernetes clusters'
+lifecycle. This project, CAPI Runtime Extensions, provides implementations of various runtime hooks that can be used in
+`ClusterClasses` across providers. This includes variables and patches that can be used across any provider to configure
+generic Kubernetes capabilities, such as configuring audit policy or HTTP proxy configuration. These capabilities are
+not provider-specific and delivering these capabilities in code instead of directly embedded in `ClusterClass`
+definitions leads to a much more robust experience via fast-feedback unit tests, as opposed to long running e2e tests.
+
+In addition to cluster resource customizations, this project enables management of essential cluster addons (e.g. CNI)
+via variable definitions, e.g. selecting a CNI provider via variables defined on the `Cluster` resource itself. The goal
+is to provide a single resource, the `Cluster`, that a user has to interact with to describe a fully-operational
+Kubernetes cluster.
+
+[clusterclass]: https://cluster-api.sigs.k8s.io/tasks/experimental-features/cluster-class/
+[clusterctl generate cluster]: https://cluster-api.sigs.k8s.io/clusterctl/commands/generate-cluster.html
+[Runtime SDK]: https://cluster-api.sigs.k8s.io/tasks/experimental-features/runtime-sdk/