change README from .md to .rst

README.md file doesn't seem to come along for the ride when
system packages are built, so we converted to .rst format,
since that seems to work.
11 jobs for fix_setup in 4 minutes and 36 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Build
passed #452958
build:debian:jessie

00:03:35

passed #452959
build:debian:stretch

00:01:41

passed #452957
build:el7

00:01:18

passed #452956
build:tarball

00:00:29

 
  Test
passed #452965
docs

00:01:00

passed #452966
syntax

00:00:47

passed #452960
test:python2.7

00:00:49

83.0%
passed #452961
test:python3.4

00:00:52

83.0%
passed #452962
test:python3.5

00:00:47

83.0%
passed #452963
test:python3.6

00:00:46

83.0%
passed #452964
test:python3.7

00:00:50

83.0%