reference rendered docs from README (#729)

Author: davepacheco

README.adoc

@@ -12,7 +12,9 @@ Omicron is open-source.  But we're pretty focused on our own goals for the fores
 
 == Documentation
 
-For design and API docs, see the https://rust.docs.corp.oxide.computer/omicron/[generated documentation].  You can generate this yourself with:
+https://docs.oxide.computer/api[Docs are automatically generated for the public (externally-facing) API] based on the OpenAPI spec that itself is automatically generated from the server implementation.  You can generate your own docs for either the public API or any of the internal APIs by feeding the corresponding OpenAPI specs (in "./openapi") into an OpenAPI doc generator.
+
+For design and internal Rust API docs, see the https://rust.docs.corp.oxide.computer/omicron/[generated documentation].  You can generate this yourself with:
 
 [source,text]
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