add missing type name

Author: RexJaeschke

standard/standard-library.md

@@ -1388,6 +1388,7 @@ The following library types are referenced in this specification. The full names
 - `global::System.Runtime.CompilerServices.ICriticalNotifyCompletion`
 - `global::System.Runtime.CompilerServices.IndexerNameAttribute`
 - `global::System.Runtime.CompilerServices.INotifyCompletion`
+- `global::System.Runtime.CompilerServices.ModuleInitializerAttribute`
 - `global::System.Runtime.CompilerServices.TaskAwaiter`
 - `global::System.Runtime.CompilerServices.TaskAwaiter<TResult>`
 - `global::System.Runtime.CompilerServices.ValueTaskAwaiter`