Mistake link in Overview section for MIR

[cocodery]

In Overview, you can see the link of [High-Level Intermediate Representation (HIR)] and [Mid-level Intermediate Representation (MIR)] in HIR lowering part and MIR lowering part separately. They are not matched. lowered to is not nessceary for MIR maybe. It's a small miktake, also you can ignore it.