RollingVwap is a separate public type (pub struct RollingVwap in
vwap.rs) and Indicator-Vwap.md already documents it in a full
"## RollingVwap (finite window)" section, but it was not directly
reachable: the Overview row added in E12 pointed at a #rollingvwap
anchor that does not exist.
Fix the Overview link to the real #rollingvwap-finite-window anchor and
add a jump-to note at the top of Indicator-Vwap.md so both public types
are reachable in one click.