Feature request: Add rate limiter

[lexfrei]

We should obey the rate limit and it's not comfortable to create limiters in each usage of the lib.
Could you please add limiter to the lib directly?

[lexfrei]

As the maintainer and author of the Terraform provider for Name.com, I'd like to add my perspective on this feature request.

Currently, I've implemented rate limiting on my side (ratelimit.go), but this approach is neither logical nor convenient from an architectural standpoint.

Rate limiting is a fundamental requirement for any consumer of the Name.com API, and having each library consumer implement their own rate limiting:

• Creates duplicated effort across projects
• Increases the risk of API abuse due to incorrect implementations
• Makes it harder to ensure consistent compliance with Name.com's rate limits

Moving rate limiting into the Go SDK itself would:

• Provide a consistent, well-tested implementation for all users
• Reduce the barrier to entry for new SDK consumers
• Ensure API rate limits are respected by default

I'm willing to contribute a PR implementing this feature if the maintainers are open to considering it for merge. Please let me know if you'd be interested in this contribution.