You need to add the maven dependency instruction to the Release-Guide.md file.
In the file tools/build-against-all-versions.sh on line 16, instead of mv lib/ksp lib/ksp-orig you need to do if [[ -d lib/ksp ]]; then mv lib/ksp lib/ksp-orig; fi, otherwise the error from mv will be thrown.

but I do get the error ERROR: /home/safff/git/krpc/doc/BUILD:50:10: Setting up python script sphinx-build failed (Exit 127) py_script-setup-sphinx-build failed: error executing command bazel-out/host/bin/doc/py_script-setup-sphinx-build
link to full log

and you need add load("@bazel_tools//tools/build_defs/repo:maven_rules.bzl", "maven_jar") to WORKSPACE file.

That error setting up sphinx build is because you need to install python virtualenv

I have made the other fixes you suggest

That error setting up sphinx build is because you need to install python virtualenv

ok. I'm will be test.