Small readme updates to reduce confusion when copying files.

INSTALL_ubuntu

@@ -70,8 +70,8 @@ We need some binaries from the codec2-dev repository:
 > cd build
 > cmake ../
 > make
-> cp src/fsk_demod ~/wenet/rx/
-> cp src/drs232_ldpc ~/wenet/rx/
+> cp ~/codec2-dev/build/src/fsk_demod ~/wenet/rx/
+> cp ~/codec2-dev/build/src/drs232_ldpc ~/wenet/rx/
 
 We also need to copy out the FSK Demod GUI Utility from this repository
 > cp ~/codec2-dev/octave/fskdemodgui.py ~/wenet/rx/