Add documentation to config file

README.md

@@ -1,13 +1,37 @@
 epp_proxy
 =====
 
-An OTP application
+An application that translates EPP over TCP connection into set of predefined HTTP calls.
+
+Serves as direct replacement for mod_epp (https://github.com/mod-epp/mod-epp), and tries to
+emulate it's behaviour to the biggest possible extent.
+
+Aside from the standard library of Erlang/OTP, it uses hackney for making HTTP requests
+and lager for logging.
 
 Build
 -----
+You need Erlang/OTP release 21 and Rebar3 to build it. No other versions than 21 were tested.
 
     $ rebar3 compile
 
+epp_proxy should be deployed as a self-contained Erlang application (release). You can create one
+with one of the following commands:
+
+```
+$ rebar3 release # Creates a release locally.
+$ rebar3 tar # Creates an archive that can be shipped to another machine
+```
+
+Configuration
+-----
+Configuration for the application tries to emulate the mod_epp configuration as close as possible
+to make migration easier.
+
+
+Deployment
+-----
+
 
 TODO
 ----

config/sys.config

@@ -1,13 +1,27 @@
 [
-  {epp_proxy, [{dev_mode, false},
+  {epp_proxy, [
+               # Enables or disable TCP connections without TLS (true/false)
+               {dev_mode, false},
+               # TCP port, only available if dev_mode is set to true.
                {tcp_port, 1700},
+               # TLS port, specified in RFC to 700, but can be set to anything else
+               # in case that is needed.
                {tls_port, 700},
+               # URL of EPP endpoints. Can be pointed at a web server (Apache/NGINX)
+               # Can contain port (https://some-host:3000/epp/session)
+               # Honors the prepended protocol (http / https).
                {epp_session_url, "https://registry.test/epp/session/"},
                {epp_command_url, "https://registry.test/epp/command/"},
                {epp_error_url, "https://registry.test/epp/error/"},
+               # Path to root CA that should check the client certificates.
                {cacertfile_path, "/opt/shared/ca/certs/ca.crt.pem"},
+               # Path to server's certficate file.
                {certfile_path, "/opt/shared/ca/certs/cert.pem"},
+
+               # Path to server's key file.
                {keyfile_path, "/opt/shared/ca/certs/key.pem"},
+
+               # Path to CRL file.
                {crlfile_path, "/opt/shared/ca/certs/key.pem"}]},
   {lager, [
     {handlers, [