How to use blockstream's REST api to retrieve JSON output on an address?
As others have said you can use https://blockstream.info/api/address/bc1qgsmfaz22lzy08wqjspd8xtm43hal5tgz4hyac6 for the JSON - the doc is in reference to running a local instance - the exact endpoint is depending on deployment, the default deployment we use has nginx forward /api/ requests to electrs without the api bit https://github.com/Blockstream/esplora/blob/master/contrib/nginx.conf.in#L32 but it depends on how people want to deploy it.

We should probably mention this in the API.md file to avoid confusion