corrected build command and added an example

README.md

 # igui_exporter
 
 # Build docker image
-docker build -t . igui_exporter
+docker build -t  igui_exporter .
 
 # Run the docker image
- docker run --rm igui_exporter --host katcp_host  --port katcp_port --igui-url http://134.104.16.96 --igui-user user --igui-pass pass --igui-parent <parent_name>:: --log-level debug
+ docker run --host katcp_host  --port katcp_port --igui-url http://134.104.16.96 --igui-user user --igui-pass pass --igui-parent <parent_name>:: --log-level debug
+
+# Example
+docker run igui_exporter --host 134.104.24.160  --port 53125 --igui-url http://134.104.16.96 --igui-user <username> --igui-pass <pass> --igui-parent EPT_TIC:: --log-level DEBUG