v0.3.1: add builder source_dir option

What's Changed

• feat: Builder source_dir parameter for non-package loads by @machow in #131
• docs: correctly escape when mentioning quarto block by @machow in #126
• docs: use quartodoc build for cli instructions by @machow in #127
• tests: python interlinks by @machow in #122
• docs: quarto install link by @machow in #129
• docs: how to document classes by @machow in #132

Full Changelog: v0.3.0...v0.3.1