Update the port assign in pocket_trk.c

[datagnss]

according to the following define in sdr_rcv.c, here is a mistake for port assign:

//      paths     (I)  output stream paths ("": no output)
//                       paths[0]: NMEA PVT solutions stream
//                       paths[1]: RTCM3 OBS and NAV data stream
//                       paths[2]: log stream
//                       paths[3]: IF data log stream

[datagnss]

1. add install script install.sh
2. update readme