Document / remove lerna bootstrap caveat

[callumacrae]

Currently, when modules are linked with lerna bootstrap, the dependant reads from the lib directory of the dependency, meaning that if you've made changes to a a component and then want to test its impact in a component that is dependant on it, you have to run lerna run build for the change to take affect (I think you also have to restart storybook - untested)

This isn't obvious at the moment - it either needs to be documented, or (better solution!) we should tell webpack to read from the src directory when referring to linked dependencies inside storybook