Create a place to highlight/document the officially maintained Go SDK

### Request Type

Missing section coverage

### What needs to be documented?

@cap10morgan maintains an official Go SDK for Harper that was previously included in a "miscellaneous" SDK page that contained many other unmaintained and unofficial Harper SDKs. We need to find a new home for the Go SDK. The docs for it do live within the repo of it itself; we do not need to consider moving those docs here. But we should at least advertise the existence of the Go SDK in our official docs. I'm not against a new SDK page somewhere.

### Where should this be documented?

_No response_

### Why is this needed?

_No response_

### Existing information

_No response_

### Priority/Impact

Medium - important but not urgent

### Are you planning to fix this issue?

No, just reporting the issue

### First-time contributor support

- [ ] I'm new to contributing and would appreciate guidance on the process
- [ ] I'd like help understanding the project structure
- [ ] I need assistance with setting up the development environment
- [ ] I'm comfortable contributing but new to this project specifically