README.md: suggest `make configure` for selecting the configuration file
README.md: suggest `make configure` for selecting the configuration file

Using configure.sh script directly is deprecated - using it with
subfolder template is cumbersome, as it has to be called with full path.
DISTORTEC/distortos,CezaryGapinski/distortos,jasmin-j/distortos,CezaryGapinski/distortos,CezaryGapinski/distortos,CezaryGapinski/distortos,jasmin-j/distortos,DISTORTEC/distortos,DISTORTEC/distortos,DISTORTEC/distortos,jasmin-j/distortos,CezaryGapinski/distortos,jasmin-j/distortos,jasmin-j/distortos