Fixed hyperlinks throughout README to point to desired sites

[cookjosh]

This is my first attempt at forking and creating a pull request! I was unsure what links you intended or where you were trying to draw values in from, but for me, the links all showed something like {{ book.officialUrl }} or something like that.

Hope it's helpful!

[bakoontz]

I think the perceived problem is that the "broken links" are actually used by honkit to generate the web version. You can see the links are correctly rendered if you look here: https://python.swaroopch.com/

[swaroopch]

Thanks for your first contribution! These placeholders are resolved when the book is built. The GitHub README does need a separate solution, but these replacements introduce some incorrect destinations, so I’m closing this approach.