Made two messages translatable. (#14751)
Summary of the issue:
PR #13798 introduced paragraph navigation in documents. Unfortunately two message added by this PR are not translatable: "No next/previous paragraph" since the gettext (_) function call has been forgotten; the translators comments are already there though.
Description of user facing changes
The message will be translatable
Description of development approach
Just added the call to the gettext function (_).
