Add VSTS status badge to readme (GH-8958)

Author: zooba

.vsts/linux-pr.yml

@@ -62,6 +62,7 @@ steps:
     uuid-dev
     xvfb
   displayName: 'Install dependencies'
+  condition: and(succeeded(), ne(variables['DocOnly'], 'true'))
 
 
 - script: ./configure --with-pydebug

README.rst

@@ -9,6 +9,18 @@ This is Python version 3.6.6+
    :alt: CPython build status on Appveyor
    :target: https://ci.appveyor.com/project/python/cpython/branch/3.6
 
+.. image:: https://python.visualstudio.com/cpython/_apis/build/status/Linux-Buildbot?branchName=3.6&label=Linux
+   :alt: CPython build status on VSTS (Linux)
+   :target: https://python.visualstudio.com/cpython/_build/latest?definitionId=6&branchName=3.6
+
+.. image:: https://python.visualstudio.com/cpython/_apis/build/status/macOS-Buildbot?branchName=3.6&label=macOS
+   :alt: CPython build status on VSTS (macOS)
+   :target: https://python.visualstudio.com/cpython/_build/latest?definitionId=5&branchName=3.6
+
+.. image:: https://python.visualstudio.com/cpython/_apis/build/status/Windows-Buildbot?branchName=3.6&label=Windows
+   :alt: CPython build status on VSTS (Windows)
+   :target: https://python.visualstudio.com/cpython/_build/latest?definitionId=4&branchName=3.6
+
 .. image:: https://codecov.io/gh/python/cpython/branch/3.6/graph/badge.svg
    :alt: CPython code coverage on Codecov
    :target: https://codecov.io/gh/python/cpython