aws-cdk-lib/aws-rds: instanceUpdateBehaviour uses British English spelling

### Describe the bug

https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_rds.InstanceUpdateBehaviour.html

Much as it pains me to report it, this is inconsistent with other spelling in the CDK that use US English spelling, such as:

- https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_cloudwatch.Color.html
- https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.SizeRoundingBehavior.html

### Regression Issue

- [ ] Select this option if this issue appears to be a regression.

### Last Known Working CDK Version

_No response_

### Expected Behavior

Consistent US English spelling.

### Current Behavior

Some British English spelling.

### Reproduction Steps

n/a

### Possible Solution

Fix the naming, possibly with a shim to allow backwards compatibility. Maybe something in the tooling could be taught to check for this as I imagine its very easy for things like this to sneak in and a pain to rectify afterwards.

### Additional Information/Context

_No response_

### CDK CLI Version

2.165.0

### Framework Version

_No response_

### Node.js Version

18

### OS

Linux

### Language

TypeScript

### Language Version

_No response_

### Other information

_No response_

Start with the InstanceUpdateBehaviour API documentation linked in the issue and trace it to the corresponding AWS CDK source or generated declaration. Determine the US-English name and the compatibility implications, then verify that the public API and its documentation use consistent spelling.

Written by the indexing model from the issue text.