Command Format: command for editing task revised
Command Format: command for editing task revised

1. change the parameter "TASK_NAME" to "TASK_UNIQUE_INDEX"

2. add example description

CS2103AUG2016-T11-C4/main,CS2103AUG2016-T11-C4/main,nightism/addressbook-level4,nightism/addressbook-level4,snehasp13/main,snehasp13/main