Update link to download neural nets

[lykahb]

The readme file points to the release page to download the nets. The recent releases did not publish them. Should the link point to this release instead? https://github.com/lightvector/KataGo/releases/tag/v1.4.5

[lightvector]

Wow, that is really out of date. The correct place is https://katagotraining.org/. It should be fixed now, thanks for pointing it out!

[HackYardo]

Perhaps it will be nicer if "About" at the right top corner of
https://github.com/lightvector/KataGo has the https://katagotraining.org/ url. Sabaki for example:

[lightvector]

Done, thank you for the suggestion!