Document GHA bug and workaround

src/docs/api/public.mdx

@@ -181,7 +181,11 @@ Once you make changes to an endpoint and merge the change into Sentry, a series
 
 1. The [`openapi` workflow in `sentry`](https://github.com/getsentry/sentry/blob/master/.github/workflows/openapi.yml) updates the schema in [sentry-api-schema](https://github.com/getsentry/sentry-api-schema) with the OpenAPI build artifact.
 2. The [`cascade-to-sentry-docs` workflow in `sentry-api-schema`](https://github.com/getsentry/sentry-api-schema/blob/main/.github/workflows/cascade-to-sentry-docs.yml) reacts to the push to `main` by triggering the [`bump-api-schema-sha` workflow in `sentry-docs`](https://github.com/getsentry/sentry-docs/blob/master/.github/workflows/bump-api-schema-sha.yml).
-3. The [`bump-api-schema-sha` workflow in `sentry-docs`](https://github.com/getsentry/sentry-docs/blob/master/.github/workflows/bump-api-schema-sha.yml) fetches the latest commit SHA from `sentry-api-schema` and writes it into the correct file, then makes and merges a PR, which kicks off a deploy of `sentry-docs` via Vercel to https://docs.sentry.io/.
+3. The [`bump-api-schema-sha` workflow in `sentry-docs`](https://github.com/getsentry/sentry-docs/blob/master/.github/workflows/bump-api-schema-sha.yml) fetches the latest commit SHA from `sentry-api-schema` and writes it into the correct file, then makes ~~and merges~~ a PR~~, which kicks off a deploy of `sentry-docs` via Vercel to https://docs.sentry.io/~~—*due to a bug in GHA, PR checks do not run when making a PR automatically from a workflow; to work around*:
+   1. Locate the "Bump API schema to $sha" [PR on `sentry-docs`](https://github.com/getsentry/sentry-docs/pulls?q=is%3Apr+%22Bump+API+schema+to%22+is%3Aopen).
+   1. Close and re-open the PR to kick off CI.
+   1. Merge manually when green.
+   1. [Write in to GitHub Support](https://support.github.com/contact?tags=rr-general-technical) reminding them that this is still a problem.
 
 ### Requesting an API to be public