advise against using schema wrapping

`wrapSchema` usually results in bad performance as it generates a proxy schema.

From looking at https://www.graphql-tools.com/docs/schema-wrapping it is unclear to me which use-cases I might wanna use `wrapSchema` and what I should prefer to use instead?

The page should start with an disclaimer and guidance on what to use, preferably with real-world examples.
E.g. For use-case X use `wrapSchema`, otherwise use Y.

Start by reviewing the schema-wrapping documentation page linked in the issue and the `wrapSchema` API guidance. Done means the page opens with a performance disclaimer, explains when `wrapSchema` is appropriate, recommends alternatives for other cases, and includes real-world examples.

Written by the indexing model from the issue text.