Update README.md about FastRunningMedian NaN Handling

[Firionus]

Hey yha 👋,
great job with this package! It seems to do exactly what it says on the box and the implementation is super elegant 👍. I've stumbled across it while searching for my package FastRunningMedian and it was interesting that you also were affected by the garbage output with NaN values. However, as of v0.2.1, FastRunningMedian doesn't output garbage with NaNs anymore 🎉 (tracking issue: Firionus/FastRunningMedian.jl#21).

I've adjusted the README slightly to include this information.

Rock on 😃

[yha]

Thanks 👍
Before writing this package, I looked at FastRunningMedian's algorithm and concluded that it would be too difficult to adapt it to deal with NaNs. But apparently it can be done! 😃

[Firionus]

That's funny, I als thought it would be really hard 😂:

Last time I started working on this I remember being so fed up with modifying my complicated algorithm that I explored SkipLists some more instead 😂.
(from the NaN issue)

But once I delved into it, things somehow just fell into place 🤷‍♂️

Have a nice day 🌻