`SetAttrs` does not handle concurrent writes

[techfg]

While potentially unlikely, calling SetAttrs could occur simultaneously from multiple go-routines, however access to the underlying slice of []slog.Attr is not protected from concurrent access.

At the very least I believe this should be mentioned in the documentation but likely should be addressed to ensure data integrity.

Happy to submit a PR if there is an appetite to address this.

[VojtechVitek]

I agree. We should document this as an intended behavior. SetAttrs() was meant to be used from the top-level handlers only, and not from within concurrent goroutines.

However, you're raising some good points about data integrity, as people will in fact use it from a goroutine eventually. Let me think about this some more. I'd like to avoid any extra locks, if possible.