Add doc for HTTP servers configuration.

docs/HTTP.md

@@ -0,0 +1,16 @@
+# HTTP in Featurer
+
+Featurer starts 2 HTTP servers:
+
+- API server.
+- CMS server.
+
+**As for now only API server will be used.**
+
+## Configuring HTTP servers
+
+Configuration for HTTP servers should be specified in environment variables. All HTTP servers uses same variables, replace `%s` with server name (`API` or `CMS`).
+
+| Key | Format | Description |
+| --- | --- | --- |
+| FEATURER_%s_SERVER_ADDRESS | `ip:port` | IP and port to listen on for requests. |

docs/INDEX.md

@@ -4,7 +4,7 @@ Welcome to Featurer's documentation!
 
 ## Administrator's corner
 
-TBW
+- [Configuring HTTP servers](HTTP.md)
 
 ## Users documentation