Remove generated types from docs (#1468)

packages/types/src/primitive/index.ts

@@ -32,7 +32,7 @@ export { default as u16 } from './U16';
 export { default as u32 } from './U32';
 export { default as u64 } from './U64';
 export { default as u128 } from './U128';
-export { default as u256 } from './U256';
+export { default as u256, default as U256 } from './U256';
 export { default as usize } from './USize';
 
 export * from './Generic';