HttpRouteKey: missing trailing underscore for method in Python documentation

### Describe the issue

This issue is seen in the Python documentation for the experimental "aws_apigatewayv2_alpha" package, under the HttpRouteKey construct.

The example uses the ".with" method, however in python the actual method name is ".with_", using the example in the documentation will result in a syntax error when trying to synthesize the template .

Example code provided in documenation
```
import aws_cdk.aws_apigatewayv2_alpha as apigatewayv2_alpha

http_route_key = apigatewayv2_alpha.HttpRouteKey.with("path", apigatewayv2_alpha.HttpMethod.ANY)
```

### Links

https://docs.aws.amazon.com/cdk/api/v2/python/aws_cdk.aws_apigatewayv2_alpha/HttpRouteKey.html

Start with the linked Python HttpRouteKey documentation page and inspect the example for the HttpRouteKey.with method. Correct the Python method spelling in the example, then verify that the documented code is valid Python and no longer produces a syntax error when used to synthesize a template.

Written by the indexing model from the issue text.