Add Appveyor docker-build badge to README.
@@ -10,6 +10,7 @@ GRR Rapid Response is an incident response framework focused on remote live fore
| End-to-end Tests | [![Build status](https://ci.appveyor.com/api/projects/status/ir4bq9577xwxt6t3?svg=true)](https://ci.appveyor.com/project/grr/grr) |
| Windows Templates | [![Build status](https://ci.appveyor.com/api/projects/status/o6y6svl9cu0j3u4x?svg=true)](https://ci.appveyor.com/project/grr/grr-5wmt5) |
| Linux & MacOS Templates | [![Build Status](https://travis-ci.org/google/grr.svg?branch=master)](https://travis-ci.org/google/grr) |
+| Docker | [![Build status](https://ci.appveyor.com/api/projects/status/siay1bi4opm97uwn?svg=true)](https://ci.appveyor.com/project/grr/grr-iqgqm) |
GRR is a python client (agent) that is installed on target systems, and
python server infrastructure that can manage and talk to clients.<br>
