Documenting Docker a little

CHANGELOG.md

@@ -3,6 +3,12 @@ Squib follows [semantic versioning](http://semver.org).
 
 ## v0.16.0 / Unreleased
 
+## v0.15.2 / 2019-09-26
+
+Chores:
+* Bump nokogiri to 1.10.4
+
+
 ## v0.15.1 / 2019-08-27
 
 Chores:

README.md

@@ -106,6 +106,30 @@ Using SublimeText? I like you already. I've written up some Squib snippets to ea
 ![Sublime Squib Snippets](https://raw.githubusercontent.com/andymeneely/squib/screencasts/sublime-squib-snippets.gif)
 
 
+## Docker
+
+Want to run in a controlled environment? We've got a [Docker image on DockerHub](https://cloud.docker.com/u/andymeneely/repository/docker/andymeneely/squib)
+
+Here's one way to run it. On the command line, go to the root of your repository. With these commands, we'll map the current directory to the `/usr/src/app` directory in the Docker image. When squib-in-docker read & writes files from there, it'll write it back out to your current directory.
+
+Assuming you have a script called hello.rb:
+
+On Windows:
+
+```
+docker run --rm -v "%cd%":/usr/src/app andymeneely/squib ruby hello.rb
+```
+
+On Macs:
+
+```
+docker run --rm -v "$PWD":/usr/src/app andymeneely/squib ruby hello.rb
+```
+
+This will create a folder called `_output` in your current directory and write the output of the script there.
+
+We're still working on ways to customize your own Docker build (e.g. document building, custom fonts, etc.) with your own Dockerfile. Pull requests and ideas welcome!
+
 
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