submitting new activities/translation

[sanuann]

from discussion with @Remi-Gau :
how to maintain added material and make maintainers' life easier (specifically - are the people who submitted new activity then in charge of maintaining them in the future?)
suggestion - should we use something like this? https://github.com/bids-standard/bids-specification/blob/master/CODEOWNERS

[satra]

moved to this project.