Problem/Motivation
A website with only one language activated is really quite different from a website with multiple languages activated. After adding a language the next step is not known.
Proposed resolution
After activating multiple languages, tell the user what steps to take now in possibly activating extra modules and make settings to content types (and possibly more, but I don't know now)
Remaining tasks
TBD
User interface changes
Possibly: show extra (modal?) screen for administrators that activate a second language
API changes
TBD