Fix comment about NANO_ARCH.  It can be set now.  Also add a warning about how it confuses TARGET and TARGET_ARCH and the need to separate the two out into independent variables.
Fix comment about NANO_ARCH.  It can be set now.  Also add a warning
about how it confuses TARGET and TARGET_ARCH and the need to separate
the two out into independent variables.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase