8: Add solution to Rust track exercise "Clock".

Created by  Aaw9nJhsNmfzFih9mKyNw9mV8CgERXJkRa1kK1Kx3LQH  on October 11, 2021
I2SHF2VRELGYCXNTJOMU554AGW3CW7LPLNE7WOWSVS4GIFHROQDAC
In channels
main
Change contents