docs: re-attach the orphaned _createRateLimitError JSDoc

[dj-jarvis]

What

_createRateLimitError had no documentation. Its JSDoc block had ended up
orphaned directly above _createApiError, separated from it by nothing but a
blank line.

/**
 * Creates a rate limit error with status code and retry-after information.
 * ...
 */
/**                                     ← only this one attaches
 * Builds an error carrying the HTTP status. ...
 */
private static _createApiError(...)

private async _createRateLimitError(...)   // ← undocumented

Why it's a bug

Two adjacent JSDoc blocks: TypeScript, IDEs and typedoc attach only the last
one to a symbol. So the first block was dead text in the source — it describes
_createRateLimitError while sitting above a method it says nothing about — and
_createRateLimitError was left with no documentation at all.

That method builds the OpenSeaRateLimitError that executeWithRateLimit in
src/utils/rateLimit.ts reads to decide whether a 429/599 is retryable, so its
documented contract (statusCode, retryAfter, responseBody) is exactly what
a reader needs and cannot find.

Most likely fallout of 59b7337 ("Attach statusCode to every error thrown for a
non-OK API response"), which added _createApiError with a new block without
removing the old one.

Fix

Move the orphaned block back onto the method it describes. Comment-only — no
behavior change.

[ryanio]

Thanks for catching this, the orphaned block was easy to miss. We've recreated the fix in our internal monorepo in ProjectOpenSea/opensea-devtools#789 (now merged), with you credited on the commit, and it will ship in the next SDK release.

This repo is a read-only mirror, so we can't merge PRs here, but we review every one. Appreciate it!