Add SPDX license & copyright headers
Some copyright information is missing because email addresses weren't publicly available.
All files in css/docsy are now licensed as Apache-2.0, just like upstream.
Testing: reuse lint
passes.
Some copyright information is missing because email addresses weren't publicly available.
All files in css/docsy are now licensed as Apache-2.0, just like upstream.
Testing: reuse lint
passes.