docs: remove Heroku integration

docs/explanations/nginx.rst

@@ -42,7 +42,7 @@ The first step is to create an Nginx configuration file that proxies requests to
 HTTPS
 -----
 
-PostgREST aims to do one thing well: add an HTTP interface to a PostgreSQL database. To keep the code small and focused we do not implement HTTPS. Use a reverse proxy such as NGINX to add this, `here's how <https://nginx.org/en/docs/http/configuring_https_servers.html>`_. Note that some Platforms as a Service like Heroku also add SSL automatically in their load balancer.
+PostgREST aims to do one thing well: add an HTTP interface to a PostgreSQL database. To keep the code small and focused we do not implement HTTPS. Use a reverse proxy such as NGINX to add this, `here's how <https://nginx.org/en/docs/http/configuring_https_servers.html>`_.
 
 Rate Limiting
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