Initial attempt at a Getting Started tutorial
Initial attempt at a Getting Started tutorial

- issue 22 [https://github.com/knative/build-pipeline/issues/22]
- steps to building task, running it then using it in a pipeline

Signed-off-by: Nader Ziada <61306b0d4f20cfca7d1222440ff271187de40866@pivotal.io>

tektoncd/pipeline,tektoncd/pipeline