Creating tutorial about nested proofs

[alv-around]

Zokrates support the composition of proofs. Meaning, you can write a proof that verifies the validity of another proof.
This can have a huge impact in scalabity by breaking down bigger proofs into smaller units, which the aggregated correctnes can be assed in a single proof.

The goal of this issue is to create a tutorial, as a first step to get acquainted with the topic

Resources

• source code: https://github.com/Zokrates/ZoKrates/blob/0.8.3/zokrates_stdlib/stdlib/snark/gm17.zok
• test: https://github.com/Zokrates/ZoKrates/blob/0.8.3/zokrates_stdlib/tests/tests/snark/gm17.zok

[alv-around]

Advantages:
➕ Can lead to less Transactions on the Blockchain
➕ Break-down of very big proofs
➕ can speedup things if underlying proofs computed in parallel (to proof)
Disadvantages:
➖ Memory overhead (400 MB x number of proofs)
➖ CPU overhead

[alv-around]

The recursive proofs only work in the current version (0.8.3) when the "parent" and "child"/"nested" proofs are compiled under the bw6_761, bls12_377 curves respectively.

For source view following thread

[alv-around]

The source code and support material is awaiting review on #2

The blog post is WIP on https://github.com/ZoKratesPlus/zokratesplus.github.io/pull/4

[alv-around]

@chGoodchild please review the linked PR, for necessary changes. Once approved it will be squashed and merged to main

[c03rad0r]

@alvaro-alonso , I added some silly questions I had following the tutorial. Perhaps it's worth addressing some of those so that your audience gets a good feeling about what happened in the tutorial.