add quantifier repetition

[petrolifero]

to write something like password <- [a-zA-Z0-9]{8}[a-zA-Z0-9]* ; to the password has minimun length of 8. or a <- [a-z]{8,10} to between 8 and 10 char.

or a <- [a-z]{8,} without upper limit, with the semantics of minimun of 8