[mlir] Fix attachInterface typo

This commit fixes the documentation typo regarding `attachInterface`.

Differential Revision: https://reviews.llvm.org/D108666

Author: loganchien

mlir/docs/Interfaces.md

@@ -285,10 +285,10 @@ int main() {
   MLIRContext context;
   /* ... */;
 
-  // Register the interface model with the type in the given context before
-  // using it. The dialect contaiing the type is expected to have been loaded
+  // Attach the interface model to the type in the given context before
+  // using it. The dialect containing the type is expected to have been loaded
   // at this point.
-  IntegerType::registerInterface<ExternalModelExample>(context);
+  IntegerType::attachInterface<ExternalModelExample>(context);
 }
 ```