updating README.rst to reflect the build changes.
updating README.rst to reflect the build changes.

hgomersall/pyFFTW,jonathanessen/pyFFTW,drwells/pyFFTW,jonathanessen/pyFFTW,simudream/pyFFTW,hgomersall/pyFFTW,jonathanessen/pyFFTW,simudream/pyFFTW,drwells/pyFFTW,simudream/pyFFTW,frederikhermans/pyfftw-arm,simudream/pyFFTW,hgomersall/pyFFTW,frederikhermans/pyfftw-arm,drwells/pyFFTW,drwells/pyFFTW