[cli] Document enhancement

On Usage Scenarios page http://jakarta.apache.org/commons/cli/usage.html

in the "Argument Options" of the ant section,

Option logfile = OptionBuilder.withArgName( "file" )
.......
.create( "file" ); should be .create("logfile")

Option find = OptionBuilder.withArgName( "file" )
.......
.create( "file" ); should be .create("find")