fix fcircuit trait github link

src/usage/frontend.md

@@ -10,7 +10,7 @@ Defining a circuit to be folded is as simple as fulfilling the `FCircuit` trait
 
 # The `FCircuit` trait
 
-To be folded with sonobe, a circuit needs to implement the [`FCircuit` trait](https://github.com/privacy-scaling-explorations/sonobe/blob/main/sonobe/src/frontend/mod.rs). This trait defines the methods that sonobe expects from the circuit to be folded. It corresponds to the $F$ function that is being folded. The trait has the following methods:
+To be folded with sonobe, a circuit needs to implement the [`FCircuit` trait](https://github.com/privacy-scaling-explorations/sonobe/blob/main/folding-schemes/src/frontend/mod.rs). This trait defines the methods that sonobe expects from the circuit to be folded. It corresponds to the $F$ function that is being folded. The trait has the following methods:
 
 ```rust
 /// FCircuit defines the trait of the circuit of the F function, which is the one being folded (ie.