Generate documentation from doc comments.

zig-ecs/build.zig

@@ -24,6 +24,11 @@ pub fn build(b: *Builder) void {
         exe.addPackagePath("ecs", "src/ecs.zig");
         exe.linkSystemLibrary("c");
         
+        exe.emit_docs = .emit;
+        const doc = b.step("docs", "Generate documentation.");
+        doc.dependOn(&exe.step);
+
+
         const run_cmd = exe.run();
         const exe_step = b.step(name, b.fmt("run {s}.zig", .{name}));
         exe_step.dependOn(&run_cmd.step);