Small improvements
The debian/watch doesn't work: if you try to run "uscan --report-status", it won't find any upstream tarball. You can find examples for github upstream repo in the manpage of uscan.
https://github.com/Raymo111/i3lock-color/tags \
(?:.*?/)?v?(\d.*)\.tar\.gz debian uupdate
You can remove the file debian/i3lock-color-docs.docs: you don't have any binary package named i3lock-color-docs, and the files mentioned in debian/i3lock-color-docs.docs don't exist.