Adding generated/fingerprinted resources to the repo

[deining]

According to this comment from the hugo creator, committing parts of the resource cache to docsy's repo seems to be reasonable:

If you are theme author, you will most likely want
to put the generated/fingerprinted resources
as part of the theme distribution, so the users
does not need to have PostCSS etc. installed to run your theme.

We should test whether with the resource cache added to our repo, docsy can possibly be built with the regular version of hugo and without installing postcss/autoprefixer.