update versions on README

7 jobs for v0.5.1 in 1 minute and 40 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Dist
passed #387896
dist:tarball

00:00:17

 
  Build
passed #387898
build:debian:stretch

00:00:34

passed #387897
build:el7

00:00:42

passed #387899
docs

00:00:53

 
  Test
passed #387901
test:debian-python2:stretch

00:00:28

22.0%
passed #387902
test:debian-python3:stretch

00:00:27

22.0%
passed #387900
test:el7-python2

00:00:25

22.0%