doc: fix misaligned columns on Firefox/Linux
13em and 234px are equivalent here. By using the same unit as is used to specify the width of the TOC, we can work around a presumed Firefox layout bug, see https://github.com/nodejs/help/issues/32.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
13em and 234px are equivalent here. By using the same unit as is used to specify the width of the TOC, we can work around a presumed Firefox layout bug, see https://github.com/nodejs/help/issues/32.