Docs/Tooltip for Tinybird destination Host > Custom

[sdairs]

Need a tooltip or some way of explaining to a user what input is expected when selecting 'Custom' in the Tinybird Destination's Host field.

[davidnmargulies]

+1

For example: to send data to AWS us-east-1, you need to enter the full URL like https://api.us-east.aws.tinybird.co

After being really annoyed using custom for my demo, I just created a pull request that adds AWS regions to the dropdown.

It's my first time trying to do a pull request so hopefully I did it right! I added you both as reviewers:
#86

Tested locally with all 3 and it worked :)