add links to revealjs and nimib

[pietroppeter]

for convenience of people that do not know neither of them

[pietroppeter]

and link to Nim, because of course people will discover about Nim thanks to Nimislides 😄

[HugoGranstrom]

Thanks, this is obvious in hindsight 😁

and link to Nim, because of course people will discover about Nim thanks to Nimislides 😄

At the rate you are advertising it for every presentation that is indeed needed 😉