Update development.markdown with install instructions and clues for running the codebase editor
Update development.markdown with install instructions and clues for running the codebase editor

Not clean-tested so likely broken.  Only tried on Ubuntu.

No instructions given for people who already have a scala install.

Not entirely clear whether/why bloop demands a single global scala version on the path.

Clues about using the codebase editor very much lacking.

unisonweb/platform,unisonweb/platform,unisonweb/platform