admin-manual: clarification about proxy protocol usage

Author: gustavosbarreto

docs/admin-manual/configuring.md

@@ -17,8 +17,7 @@ Default: 22
 
 ### :arrow_right: `SHELLHUB_PROXY`
 
-Set this variable to `true` if you are running a reverse proxy or a load balancer
-in front of ShellHub.
+Set this variable to `true` if you are running a Layer 4 load balancer with proxy protocol in front of ShellHub.
 
 !!! danger ""
 	This option is required when running ShellHub in production with SSL enabled.

docs/admin-manual/production-deployment.md

@@ -47,4 +47,4 @@ services:
 This is commonly achieved by running Nginx with your certificates on your
 Docker host, service or load balancers in-front of the running container.
 
-!!! info "Don't forget to set `SHELLHUB_PROXY=true` environment when putting a proxy in-front of ShellHub."
+!!! info "Don't forget to set [`SHELLHUB_PROXY`](/admin-manual/configuring/#shellhub_proxy) environment when putting a Layer 4 load balancer with proxy protocol in-front of ShellHub."