Add a readme with basic instructions.

Change-Id: I00501ac713f88f36146e9681c8ac44f26b8f94bf
Add a readme section about tests.

Change-Id: Iba82f7dc40961cae33120a6a1a03c5f981dab291
Merge pull request #1 from PeterJCLaw/add-readme

Add a readme with basic instructions.