Flesh out documentation of clients

pages/spicedb/getting-started/client-libraries.mdx

@@ -2,7 +2,7 @@
 
 SpiceDB is primarily accessed by a [gRPC] API and thus client libraries can be generated for any programming language.
 
-AuthZed builds and maintains client libraries for the following languages:
+AuthZed builds and maintains gRPC client libraries for the following languages:
 
 - [Go](https://github.com/authzed/authzed-go)
 - [Node](https://github.com/authzed/authzed-node)
@@ -11,6 +11,29 @@ AuthZed builds and maintains client libraries for the following languages:
 - [Java](https://github.com/authzed/authzed-java)
 - [Dotnet](https://github.com/authzed/authzed-dotnet)
 
+Because the above libraries are generated from protobuf definitions in our [API repo],
+the primary documentation for the gRPC API is in the [buf documentation] for SpiceDB's services.
+The gRPC client documentation associated with each host language will also be helpful for putting together invocations.
+Additionally, there are `example` directories in the client libraries that provide example usages.
+
+## HTTP Clients
+
+SpiceDB exposes an HTTP API when run with the `--http-enabled` flag.
+While Authzed doesn't officially maintain HTTP client libraries, there are [OpenAPI] docs available
+both in [the authzed-go git repo](https://github.com/authzed/authzed-go/blob/main/proto/apidocs.swagger.json)
+and served by a SpiceDB instance running the HTTP server.
+For example:
+
+```sh
+docker run --rm -p 50051:50051 -p 8443:8443 authzed/spicedb serve --http-enabled --grpc-preshared-key <preshared key>
+
+curl localhost:8443/openapi.json
+```
+
+The OpenAPI JSON can then be converted into a client using a tool like [openapi-ts] or [openapi-python-client].
+
+## Other Clients
+
 AuthZed also develops [zed], a command-line client for interacting with the SpiceDB API.
 
 You can find more languages and integrations maintained by the community in the [Clients section] of the [Awesome SpiceDB] repository.
@@ -19,3 +42,8 @@ You can find more languages and integrations maintained by the community in the
 [zed]: https://github.com/authzed/zed
 [clients section]: https://github.com/authzed/awesome-spicedb#clients
 [awesome spicedb]: https://github.com/authzed/awesome-spicedb
+[api repo]: https://github.com/authzed/api
+[buf documentation]: https://buf.build/authzed/api/docs/main:authzed.api.v1
+[openapi]: https://www.openapis.org/
+[openapi-ts]: https://github.com/hey-api/openapi-ts
+[openapi-python-client]: https://github.com/openapi-generators/openapi-python-client