README typo

[genkiiii]

Hello,

Thank you so much for the nice tools.

There is a typo in the decode explanation in README.

candump any | dbcppp decode --bus=vcan0,file1.dbc --bus=vcan1,file2.dbc should be candump any | dbcppp decode --bus=vcan0:ile1.dbc --bus=vcan1:file2.dbc