You could try to add
<project name="LineageOS/android_vendor_lineage" path="vendor/lineage" remote="github" revision="lineage-16.0" />
in top of projects (after the “remove”) …
But to be honest, I don’t think this will be enough for you build to success.
As stated here, they are preliminary steps, which compatibility with /e/ Docker build system is unknown to me …
If you want to stick to Docker, you may try to run commands 3-6 of this README directly in your /srv/e-os-i9100/src/Pie directory, before launching Docker command (not sure about the “Pie”, is it “P” ?).
You may miss repo and git commands, and have to install them (they are included in Docker image, so normally you don’t need them in your “host” OS).
As an alternative, you may give up with the Docker method, and read this : [HOWTO] Build /e/ without docker for non LineageOS supported devices
Kinda difficult for a first build !