add note about compression level

> 1. Bad default configuration
> It uses 11 for brotli by default which is a very bad choice for real-time applications (such as web apps). Such a high level is especially slow on brotli, which will hurt overall performance unless changed explicitly. It should only be reserved for operations where latency is not important. [[ref](https://github.com/developmentseed/starlette-cramjam/blob/d3e98721fad5907b4d81201e31d95035b6a4552d/starlette_cramjam/compression.py#L9)]

ref https://github.com/stac-utils/stac-fastapi/issues/830#issuecomment-2815523855

answer:

I've raised this in the upstream lib couple months ago https://github.com/milesgranger/cramjam/issues/187

Because the level of compression is configurable I didn't wanted to change it to not break anything!