Tries to push a document to the logged in user identified by userId. If the user is not logged in the request will be discarded. The pushed document must be in the state ACTIVE or ARCHIVED. By setting useLatestVersion to true, the newest version of an instruction which is either in the state ACTIVE or ARCHIVED will be pushed to the user. A lang parameter can be send in the body to determine the language of the Document which will be opened. A HTTP 404 Not Found error will be returned if no user with userId or no valid Document with documentId exists. A HTTP 400 Bad Request error will be returned if useLatestVersion is either not set or false while the Instruction is not in the state ACTIVE or ARCHIVED.