Use more consistent markdown syntax in documentation.

src/site/markdown/architecture/attitudes.md

src/site/markdown/architecture/bodies.md

src/site/markdown/architecture/errors.md

src/site/markdown/architecture/forces.md

src/site/markdown/architecture/frames.md

src/site/markdown/architecture/orbits.md

src/site/markdown/architecture/propagation.md

src/site/markdown/architecture/tessellation.md

src/site/markdown/architecture/time.md

src/site/markdown/architecture/tle.md

src/site/markdown/architecture/utils.md

src/site/markdown/building.md

src/site/markdown/configuration.md

src/site/markdown/contact.md

src/site/markdown/contributing.md

src/site/markdown/downloads.md

src/site/markdown/faq.md

src/site/markdown/guidelines.md

src/site/markdown/index.md

src/site/markdown/sources.md