Fix reference to deprecated SIGUP call (#1284)
Fix reference to deprecated SIGUP call (#1284)

This updates the instructions about sending a `SIGUP` call (deprecated) to `SIGUSR1`, and links to relevant docs: http://postgrest.org/en/v5.2/admin.html#schema-reloading

Per the docs:

> As of PostgREST v5.1 reloading with SIGHUP is deprecated, it’s still supported but will be removed in v6.0. SIGUSR1 should be used instead.

See [5.1.0 CHANGELOG](https://github.com/PostgREST/postgrest/blob/d32f373e1ee95ba68141a3f3a48ab8c94ea2453a/CHANGELOG.md#deprecated) or https://github.com/PostgREST/postgrest/issues/724
diogob/postgrest,begriffs/postgrest,steve-chavez/postgrest,steve-chavez/postgrest