How to add build step that serves my emitted docs?

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2

on linux

const install_docs = b.addInstallDirectory(.{
    .install_dir = .prefix,
    .install_subdir = "docs",
    .source_dir = exe.getEmittedDocs(),
});

const doc_step = b.step("docs", "emit docs");
doc_step.dependOn(&install_docs.step);

const open_docs = b.addSystemCommand(&.{"xdg-open"});
open_docs.step.dependOn(doc_step);
open_docs.addFileArg(try exe.getEmittedDocs().join(b.allocator, "index.html"));

const show_doc_step = b.step("open docs", "open docs");
show_doc_step.dependOn(&open_docs.step);