message: Update packages/@orbit/memory/README.md
diff: An in-memory data source that supports complex querying and updating. Because
  memory sources maintain data in immutable data structures, they can be efficiently
  -forked. Forked source can diverge from the master source, and then the changes
  +forked. Forked sources can diverge from the master source, and then any changes
  can be merged later.
  ## Installation
  