Bump up Scala and Java sections one header level [CI SKIP]
Bump up Scala and Java sections one header level [CI SKIP]

This allows those sections to automatically appear in the table of
contents sidebar in Docusaurus for the new website.

xeno-by/scalameta,olafurpg/scalameta,olafurpg/scalameta,olafurpg/scalameta,xeno-by/scalameta,scalameta/scalameta,scalameta/scalameta,scalameta/scalameta,scalameta/scalameta,scalameta/scalameta,xeno-by/scalameta