Consider disallowing redirects for API requests that redirect from POST to GET

[philvarner]

I recently had a situation where a server that used an https URL incorrectly had http links in it's link relations. The result of this was that the underlying http client library in pystac-client got a redirect from a POST /search request, and then retried with a GET /search request. However, this didn't work correctly, since the POST body was not also re-constructed as GET query parameters, so the search instead resulted in all items being returned.

1. Changing the default behavior of redirects like this would be difficult to do outside of a major release.
2. Adding some documentation about ensuring that the response link rels match the requested URL could be useful.

[nlebovits]

I'm thinking it would make sense to add a short section to the usage page after "Using custom certificates", maybe called "Troubleshooting HTTPS/HTTP redirect issues". This would include 1) what the issue is and where it comes from, 2) how to identify if it's happening, and 3) possible workarounds, e.g., manually disabling automatic redirects.

@philvarner Could you share a reprex? That would be helpful for me in better understanding what's going on and in writing up the docs.