Add JSON schema and guidance on API usage to docs

- Add a hidden command to generate JSON schema
- Wire it up to the new `make update-generated`
- Describe how to use it in the docs

Signed-off-by: Colin Walters <[email protected]>

docs/src/SUMMARY.md

@@ -27,6 +27,7 @@
 - [`man bootc-rollback`](man/bootc-rollback.md)
 - [`man bootc-usr-overlay`](man/bootc-usr-overlay.md)
 - [`man bootc-fetch-apply-updates.service`](man-md/bootc-fetch-apply-updates-service.md)
+- [Controlling bootc via API](bootc-via-api.md)
 
 # Using `bootc install`
 

docs/src/bootc-via-api.md

@@ -0,0 +1,29 @@
+# Using bootc via API
+
+At the current time, bootc is primarily intended to be
+driven via a fork/exec model. The core CLI verbs
+are stable and will not change.
+
+## Using `bootc edit` and `bootc status --json --format-version=0`
+
+While bootc does not depend on Kubernetes, it does currently
+also offere a Kubernetes *style* API, especially oriented
+towards the [spec and status and other conventions](https://kubernetes.io/docs/reference/using-api/api-concepts/).
+
+In general, most use cases of driving bootc via API are probably
+most easily done by forking off `bootc upgrade` when desired,
+and viewing `bootc status --json --format-version=0`.
+
+## JSON Schema
+
+The current API is classified as `org.containers.bootc/v1alpha1` but
+it will likely be officially stabilized mostly as is. However,
+you should still request the current "v0" format via an explicit
+`--format-version=0` as referenced above.
+
+There is a [JSON schema](https://json-schema.org/) generated from
+the Rust source code available here: [host-v0.schema.json](host-v0.schema.json).
+
+A common way to use this is to run a code generator such as
+[go-jsonschema](https://github.com/omissis/go-jsonschema) on the
+input schema.