Adding solution to ssl certification issue to README.md

[onrdmr]

Huge thanks for this library. Adding how can we set ssl certificate would made our readme.md well documented.

create extension http; 
SELECT http_set_curlopt('CURLOPT_CAINFO', 'C:/Program Files/PostgreSQL/15/ssl/certs/ca-bundle.crt'); 
SET http.timeout_msec = 5000;

[robe2]

I think I have it in the README for the http download for windows. I don't think it's appropriate in this README since it seems to only be an issue on windows. Or are you having the issue elsewhere?

BTW I'm in the middle of packaging new http for windows which will include PG17. Hoping to be done by that on Monday.