Improving save workflow for mobile editing

See https://trello.com/c/hRCB0ed1/3-3-improve-save-workflow-for-editing

Make it more clear what users are supposed to on the preview/summary
screen and provide them with some examples of good edit summaries.

Change-Id: I23eb40c65a7ba5d19b6cf57413569d48c91c8505
Merge "Improving save workflow for mobile editing"