Restructured partials

docs/customization.md

docs/getting-started.md

material/base.html

material/partials/fonts.html

material/partials/footer.html

material/partials/language.html

material/partials/search.html

material/partials/source.html

material/partials/svgs.html

material/partials/toc.html

src/base.html

src/partials/fonts.html

src/partials/footer.html

src/partials/language.html

src/partials/search.html

src/partials/source.html

src/partials/svgs.html

src/partials/toc.html