Add DNS for mul.wikisource.org

For creating a redirect from mul.wikisource.org to wikisource.org:
Ic43d773b631617110cf4e4068961b02db3a7f1e8

Bug: 73407
Change-Id: I201150ea64f778a704b3915ed9bd326424f38db9
Merge "Add DNS for mul.wikisource.org"