Add a README.md as discussed at solid-contrib#3

As further discussed at [Suggestion: Tutorial MD should be part of this project · Issue solid-contrib#3 · solid/profile-viewer-tutorial](solid-contrib#3)
it would be easier to report issues and keep the tutorial and its code in sync if the text for both of them was in this repo.

README.md

@@ -0,0 +1,21 @@
+# profile-viewer-tutorial for Solid applications
+
+This is the code behind the tutorial [Make a Solid app on your lunch break](https://solid.inrupt.com/docs/app-on-your-lunch-break)
+
+An easy way to use it is to clone this tutorial locally:
+
+    git clone [email protected]:solid/profile-viewer-tutorial.git
+
+and then, as you follow the instructions in the tutorial, follow along here step-by-step with the commits to this repository.
+
+E.g., follow the initial steps to get yourself a Solid pod.  Then
+
+    git checkout tutorials/lunch-break/steps/01
+
+and, as instructed, set up a local web server to serve the contents of this repository.
+
+Then move to the next step,
+
+git checkout tutorials/lunch-break/steps/02
+
+refresh your browser, and so forth.