add environment values to readme

README.md

@@ -18,6 +18,13 @@ this is a dynamically built gotty container
 - base image + curl, jq and tmux
 - sid main repo available
 
+## environment values
+port - sets the port the gotty web-ui runs at (def. 8080)
+userpass - sets a username and password for the webui (optional, def. none)
+title - set application title (browser and tmux session title, def. gotty)
+pkgs - additional packages to install when the container is started (optional, def. none)
+command - the command to run (required, def. none/pfetch)
+
 ## compose
 this example can also be found in the repo
 
@@ -38,3 +45,5 @@ services:
      - pkgs=htop
      - command=htop
 ```
+
+