use a separate build.zig for the example

This gives a more concrete example of how to use vulkan-zig, including
build commands as how a downstream user would use vulkan-zig.

examples/build.zig

@@ -0,0 +1,50 @@
+const std = @import("std");
+
+const vkgen = @import("vulkan_zig");
+const ShaderCompileStep = vkgen.ShaderCompileStep;
+
+pub fn build(b: *std.Build) void {
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+    const maybe_override_registry = b.option([]const u8, "override-registry", "Override the path to the Vulkan registry used for the examples");
+
+    const registry = b.dependency("vulkan_headers", .{}).path("registry/vk.xml");
+
+    const triangle_exe = b.addExecutable(.{
+        .name = "triangle",
+        .root_source_file = .{ .path = "triangle.zig" },
+        .target = target,
+        .link_libc = true,
+        .optimize = optimize,
+    });
+    b.installArtifact(triangle_exe);
+    triangle_exe.linkSystemLibrary("glfw");
+
+    const vk_gen = b.dependency("vulkan_zig", .{}).artifact("vulkan-zig-generator");
+    const vk_generate_cmd = b.addRunArtifact(vk_gen);
+
+    if (maybe_override_registry) |override_registry| {
+        vk_generate_cmd.addFileArg(.{ .path = override_registry });
+    } else {
+        vk_generate_cmd.addFileArg(registry);
+    }
+
+    triangle_exe.root_module.addAnonymousImport("vulkan", .{
+        .root_source_file = vk_generate_cmd.addOutputFileArg("vk.zig"),
+    });
+
+    const shaders = ShaderCompileStep.create(
+        b,
+        &[_][]const u8{ "glslc", "--target-env=vulkan1.2" },
+        "-o",
+    );
+    shaders.add("triangle_vert", "shaders/triangle.vert", .{});
+    shaders.add("triangle_frag", "shaders/triangle.frag", .{});
+    triangle_exe.root_module.addImport("shaders", shaders.getModule());
+
+    const triangle_run_cmd = b.addRunArtifact(triangle_exe);
+    triangle_run_cmd.step.dependOn(b.getInstallStep());
+
+    const triangle_run_step = b.step("run-triangle", "Run the triangle example");
+    triangle_run_step.dependOn(&triangle_run_cmd.step);
+}

examples/build.zig.zon

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+.{
+    .name = "vulkan-zig-examples",
+    .version = "0.1.0",
+    .dependencies = .{
+        .vulkan_zig = .{
+            .path = "..",
+        },
+        .vulkan_headers = .{
+            .url = "https://github.com/KhronosGroup/Vulkan-Headers/archive/v1.3.283.tar.gz",
+            .hash = "1220a7e73d72a0d56bc2a65f9d8999a7c019e42260a0744c408d1cded111bc205e10",
+        },
+    },
+    .paths = .{""},
+}