readme: add build.zig gen step example

README.md

@@ -8,8 +8,36 @@ CI tested weekly with latest zig version.
 
 This project depends on packaged `flatc` compiler @v23.3.3, built with zig using [a fork of google/flatbuffers](https://github.com/travisstaloch/flatbuffers).
 
-# Gen Steps
-To auto generate code from a flatbuffers file in your build.zig see the example in [#18](https://github.com/travisstaloch/flatbufferz/pull/18).
+# Gen Step
+To generate code from a flatbuffers file in your build.zig:
+
+```console
+zig fetch --save git+https://github.com/travisstaloch/flatbufferz
+```
+
+```zig
+const std = @import("std");
+
+pub fn build(b: *std.Build) !void {
+    const exe = b.addExecutable(.{
+        // ...
+    });
+
+    const fbz_dep = b.dependency("flatbufferz", .{});
+    const gen_step = try @import("flatbufferz").GenStep.create(
+        b,
+        fbz_dep.artifact("flatc-zig"),
+        &.{"src/myschema.fbs"},
+        &.{},
+        "flatc-zig",
+    );
+
+
+    exe.root_module.addImport("generated", gen_step.module);
+    exe.root_module.addImport("flatbufferz", fbz_dep.module("flatbufferz"));
+}
+
+```
 
 
 # Usage