docs: add usage instructions

README.md

@@ -5,3 +5,24 @@ A community driven package registry for <a href="https://github.com/williamboman
 Refer to [CONTRIBUTING.md](./CONTRIBUTING.md) for contribution guidelines.
 
 Compiled registry contents are available via [releases](https://github.com/mason-org/mason-registry/releases).
+
+## Usage
+
+To use this registry you simply need to add the string `"github:AstroNvim/mason-registry"` to the `registries` list of
+the `mason.nvim` configuration that is passed to the `require("mason").setup()` function.
+
+**Lazy.nvim**
+
+```lua
+return {
+    "williamboman/mason.nvim",
+    opts = {
+        registries = {
+            -- default Mason registry has highest priority
+            "github:mason-org/mason-registry",
+            -- Add the AstroNvim mason registry
+            "github:AstroNvim/mason-registry",
+        },
+    },
+}
+```