Added some info about usage

Author: fabiang

README.md

@@ -11,4 +11,20 @@ All other parts of the library are licenced under [BSD 2-Clause License](LICENSE
 
 ## Usage
 
+Connect to an Sqlsrv inside another container (Container name is "my-sqlsrv"):
 
+```bash
+docker run -it --link my-sqlsrv:sqlsrv fabiang/sqlcmd -S sqlsrv -U sa
+```
+
+Or to any other server on the network:
+
+```bash
+docker run -it fabiang/sqlcmd -S some-sqlsrv -U sa
+```
+
+Get available options with:
+
+```bash
+docker run -it fabiang/sqlcmd '-?'
+```