better document for SDKs - lookupin xattrs

better document for SDKs - lookupin xattrs

while the current documentation does mention the feature - it appears that there was a conscious decision to down-play it. Maybe you could provide some guidance there.

“They are not intended for use in general applications,”

https://docs.couchbase.com/dotnet-sdk/current/howtos/subdocument-operations.html#extended-attributes
https://docs.couchbase.com/python-sdk/current/howtos/subdocument-operations.html#extended-attributes
https://docs.couchbase.com/c-sdk/current/howtos/subdocument-operations.html#extended-attributes
https://docs.couchbase.com/go-sdk/current/howtos/subdocument-operations.html#extended-attributes
https://docs.couchbase.com/java-sdk/current/howtos/subdocument-operations.html#extended-attributes
https://docs.couchbase.com/nodejs-sdk/current/howtos/subdocument-operations.html#extended-attributes
https://docs.couchbase.com/php-sdk/current/howtos/subdocument-operations.html#extended-attributes
https://docs.couchbase.com/python-sdk/current/howtos/subdocument-operations.html#extended-attributes
https://docs.couchbase.com/ruby-sdk/current/howtos/subdocument-operations.html#extended-attributes
https://docs.couchbase.com/scala-sdk/current/howtos/subdocument-operations.html#extended-attributes

Server doc that SDK doc can reference :
https://docs.couchbase.com/server/current/learn/data/extended-attributes-fundamentals.html