add test files

examples/src/01-01.zig

@@ -7,7 +7,7 @@ pub fn main() !void {
     defer _ = gpa.deinit();
     const allocator = gpa.allocator();
 
-    const file = try fs.cwd().openFile("build.zig", .{});
+    const file = try fs.cwd().openFile("tests/hello-world.txt", .{});
     defer file.close();
 
     const rdr = file.reader();

examples/src/02-01.zig

@@ -22,7 +22,7 @@ pub fn main() !void {
     defer _ = gpa.deinit();
     const allocator = gpa.allocator();
 
-    const file = try fs.cwd().openFile("build.zig", .{});
+    const file = try fs.cwd().openFile("tests/hello-world.txt", .{});
     defer file.close();
 
     const digest = try sha256_digest(allocator, file);

examples/tests/hello-world.txt

@@ -0,0 +1,3 @@
+Hello Zig. 😁
+
+I love Zig very much!

src/intro.md

@@ -13,7 +13,7 @@ Each recipe is accompanied by an illustrative example named after its correspond
 
 # Contributing
 
-Anyone is welcome to contribute. This project use [prettier](https://prettier.io/) to format markdown files, make sure to execute `make lint` before open PR.
+This cookbook is a work in progress, and we welcome contributions from the community. If you have a favorite recipe that you'd like to share, please submit a pull request.
 
 # Acknowledgment