This page only exists to separate the subtheme module pages.
Subtheme modules work as so:
a page named as so – subtheme-[slug of subtheme] will be detected and the content inserted into that subtheme page, near the end of other content.
We have designed a subtheme module Pattern as a content module to go on this subtheme page. On the subtheme page, click to add a block, then look for the Pattern under the patterns tab.