Follow-up to typography changes to Vector

Getting rid of pre rule per discussion.

Changing line-height: 0 for sup tags to line-height: 1 per
suggestion at https://gerrit.wikimedia.org/r/#/c/120978/ and
also adding sub.

Also update release notes.

Bug: 49965
Change-Id: Ic9dc071d1868b16a46eef1d7c41dc6abe12fa7b7
Merge "Follow-up to typography changes to Vector"