Added settings should filter out well known settings

[rustyconover]

Hi DuckDB Team and @szarnyasg,

Several of my extensions load httpfs in order to make web requests. While reviewing the Community Extensions site, I noticed that httpfs settings appear in the “Added Settings” section of the extension docs.

For example:

https://duckdb.org/community_extensions/extensions/airport.html

To avoid confusion, I’d suggest either removing these well-known httpfs settings from the list, or ensuring httpfs is loaded first.

Thanks,
Rusty