Update DEVELOP to use latest rust stable
Update DEVELOP to use latest rust stable

Do not document a specific version, use the latest stable.

Genymobile/gnirehtet,WPO-Foundation/gnirehtet,Genymobile/gnirehtet,WPO-Foundation/gnirehtet,WPO-Foundation/gnirehtet,Genymobile/gnirehtet,WPO-Foundation/gnirehtet