Update README.md

README.md

@@ -2,3 +2,23 @@
 
 Libraries and primitives for Bitcoin, written in Zig.
 
+# Zig Official Package Manager
+
+To install `bitcoin-zig`, you need to run the following command in your root folder with `build.zig`:
+
+```bash
+zig fetch --save git+https://github.com/zig-bitcoin/bitcoin-zig#f3af13008b088796697fc656e26d8c2ddf73dc18
+```
+
+where `f3af13008b088796697fc656e26d8c2ddf73dc18` is the commit hash.
+
+Then, in your `build.zig`, you need to add our module:
+
+```zig
+const bitcoin_zig = b.dependency("bitcoin-zig", .{
+    .target = target,
+    .optimize = optimize,
+});
+
+exe.root_module.addImport("bitcoin", bitcoin_zig.module("bitcoin"));
+```