README+=link to Tracing re: profiling-with-tracing

Definitely makes sense to add tracing there, thanks!
Do you think it would make sense to keep it alphabetized?
The tracing logo is very large on desktop. I'd rather keep it smaller since it's cosmetic only/not conveying information. We could just use the left half of the logo and crop down the whitespace around it? Or leave the logo out would be fine too.
It might make sense to very briefly summarize what tracing is and why it's useful since it's different from the others. I'll give it a try:
- "The tracing backend injects tracing span!() macros that match the lifetime of the profiling macros. tracing uses callbacks rather than inlining specific pre-determined code, so it is more flexible than profiling (at the cost of more lines of code and potentially non-zero overhead). This allows existing and new tracing-compatible handlers to work with profiling."

aclysma / profiling