fix(README): link to tutorial
fix(README): link to tutorial

johoelzl/lean,leanprover/lean,digama0/lean,leanprover-community/lean,digama0/lean,rlewis1988/lean,leanprover/lean,fgdorais/lean,avigad/lean,leodemoura/lean,Kha/lean,leanprover-community/lean,digama0/lean,digama0/lean,johoelzl/lean,Kha/lean,fpvandoorn/lean,Kha/lean,dselsam/lean,Kha/lean,leodemoura/lean,avigad/lean,avigad/lean,leanprover-community/lean,johoelzl/lean,rlewis1988/lean,rlewis1988/lean,fpvandoorn/lean,fpvandoorn/lean,avigad/lean,fpvandoorn/lean,avigad/lean,digama0/lean,leodemoura/lean,digama0/lean,leodemoura/lean,avigad/lean,fgdorais/lean,rlewis1988/lean,johoelzl/lean,leanprover-community/lean,leodemoura/lean,fgdorais/lean,leanprover-community/lean,leanprover/lean,fgdorais/lean,leanprover/lean,dselsam/lean,Kha/lean,Kha/lean,dselsam/lean,fgdorais/lean,fpvandoorn/lean,rlewis1988/lean,fpvandoorn/lean,johoelzl/lean,dselsam/lean,rlewis1988/lean,leodemoura/lean,dselsam/lean,leanprover-community/lean,fgdorais/lean,dselsam/lean,johoelzl/lean,leanprover/lean,leanprover/lean