Update readme with instructions

Author: benrowe

README.md

@@ -4,5 +4,8 @@ Implements [MySQL to SQLite3][link-sql] as a docker utility
 
 ## How to use
 
+```
+docker run --rm -v ${PWD}:/output benrowe/mysql-to-sqlite3 mysql2sqlite -f /output/export.sqlite3 -d database_name -u username -h host.docker.internal -p password
+```
 
-[link-sql]:https://github.com/techouse/mysql-to-sqlite3
+[link-sql]:https://github.com/techouse/mysql-to-sqlite3