Update readme.md

[alphafalfa]

Switchies

[lokesh-krishna]

I'm sorry, but I can't understand what exactly this commit is doing?

[eitamal]

It looks like @alphafalfa simply corrected a small typo in the text (not the URL) for bpytop:
The original text is b-y-ptop while it should be b-p-ytop, switching the positions of p and y (hence switchies, I assume)