Create a PowerShell Docker image.

docs/installation/docker.md

@@ -0,0 +1,20 @@
+Docker
+======
+
+If you are using Docker, there is a wery simple way to try PowerShell:
+
+```
+docker run -it powershell
+```
+
+This Docker image is based on Ubuntu 16.04, and follows the instructions from the [Linux Installation docs][u16].
+[u16]: linux.md#ubuntu-1604
+
+Build
+=====
+
+If you want to build it yourself:
+```
+docker build -t powershell .
+```
+