Describe Support tickets severity

[YanicNeon]

When the new Support Form was introduced (See https://github.com/neondatabase/cloud/issues/6140), it also introduced the concept of severity.
During the case creation, our customers can now select the severity that best describes the issue reported.
To help our customers select the correct severity level, a few examples for each severity level have been documented (See: https://www.notion.so/neondatabase/Support-Ticket-Severity-Levels-8bab6f70fd5c46c689e74fe53d231ee0?pvs=4).

Could you please review the examples provided and suggest descriptions for each of the four severity level used?
Eventually, those severity level would need to be documented on our website.

Thanks!

[YanicNeon]

@danieltprice assigning you this GH issue as per our discussion.
If you need anything, please, let me know.