Update README.md

Author: MrDave1999

src/Attributes/README.md

@@ -1,3 +1,35 @@
 # CPlugin.Net.Attributes
 
-A simple library that includes the `PluginAttribute` type to be used by plugins.
+A simple library that includes the [PluginAttribute](https://mrdave1999.github.io/CPlugin.Net/api/CPlugin.Net.PluginAttribute.html) type to be used by plugins.
+
+### Example
+
+`IPluginStartup` represents the contract and can reside in its own project called `MyApp.Contracts`.
+
+Each plugin must implement the contract in this way:
+```cs
+public class Startup : IPluginStartup 
+{ 
+
+}
+```
+
+And then add this line before the namespace declaration:
+```cs
+[assembly: Plugin(typeof(Startup))]
+```
+
+**Complete example:**
+```cs
+using Project.MyPlugin1;
+using MyApp.Contracts;
+using CPlugin.Net;
+
+[assembly: Plugin(typeof(Startup))]
+namespace Project.MyPlugin1;
+
+public class Startup : IPluginStartup 
+{ 
+
+}
+```