Documentation: Update README's to reflect that building uses o1js instead of Mina

[MartinMinkov]

There is stale documentation such as this file, that needs to be updated to make mention of o1js being the root project to build from now.

[shimkiv]

Also will be good to replace snarkyjs with o1js: https://github.com/search?q=repo%3Ao1-labs%2Fo1js-bindings%20snarkyjs&type=code
(including sub-modules inversion description)

[shimkiv]

There also files left with old name like build-snarkyjs...

[MartinMinkov]

There also files left with old name like build-snarkyjs...

Which files are you referring to? In the bindings repo, I only see mention of snarkyjs inside README documentation

[shimkiv]

Oh my apologies I was using old reference in o1js. No files, only readme indeed.