Merge "Update m help text with guidance on parallelism"

source build/envsetup.sh    # Add "lunch" (and other utilities and variables)

                            # to the shell environment.

lunch [<product>-<variant>] # Choose the device to target.

m -j [<goals>]              # Execute the configured build.

m [<goals>]                 # Execute the configured build.

Usage of "m" imitates usage of the program "make".

See '"${SCRIPT_DIR}"'/Usage.txt for more info about build usage and concepts.

The parallelism of the build can be set with a -jN argument to "m".  If you

don't provide a -j argument, the build system automatically selects a parallel

task count that it thinks is optimal for your system.

Common goals are:

    clean                   (aka clobber) equivalent to rm -rf out/