Uses a supported field for languages.

As discussed here, this field is a valid upstream field.

https://github.com/schemaorg/schemaorg/issues/1688#issuecomment-438587953

looks good, i think we should start merging to develop instead of master so that we can do effective releases of the spec when merged to master and tagged.....

changed the description

changed target branch from master to develop

Good idea, I updated the MR.

What is blocking here from merge?

mentioned in commit 174a83d6

merged