Update README for early collaboration

README.md

@@ -1,9 +1,22 @@
-# Rapid Experiments Schemas ![CircleCI](https://img.shields.io/circleci/build/github/mozilla/rapid-experiments-schemas)
+# Rapid Experiments Shared ![CircleCI](https://img.shields.io/circleci/build/github/mozilla/rapid-experiments-shared)
 
-This is a place to define schemas used across the rapid experiments program.
+This is a place to define data and schemas used across the rapid experiments
+program.
 
 Any data that moves between systems should have a schema defined here. Schemas
-are defined using Typescript, and automatically converted to JSON Schema.
+are defined using Typescript, and automatically converted to JSON Schema. Any
+data that needs to be re-used by multiple systems should be stored here to be
+shared.
+
+## Working on this repo
+
+Common tasks are defined as Yarn scripts.
+
+```shell
+yarn install
+yarn build
+yarn test
+```
 
 ## Using the schemas