Add top-level README

Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Status Job ID Name Coverage
  Test
failed #3543
test

00:11:22

failed #3218
test

00:00:30

failed #3202
test

 
Name Stage Failure
failed
test Test
pep8 installdeps: flake8
pep8 installed: flake8==3.5.0,mccabe==0.6.1,pycodestyle==2.3.1,pyflakes==1.6.0
pep8 runtests: PYTHONHASHSEED='1087765144'
pep8 runtests: commands[0] | flake8 patchwork patchwork/bin/pwclient git-pw/git-pw
___________________________________ summary ____________________________________
py27-django111: commands succeeded
ERROR: py36-django111: commands failed
pep8: commands succeeded
ERROR: Job failed: exit code 1