doc: change name function

Author: franckgaga

docs/src/internals/predictive_control.md

@@ -12,7 +12,7 @@ The prediction methodology of this module is mainly based on Maciejowski textboo
 ## Controller Construction
 
 ```@docs
-ModelPredictiveControl.init_ΔUtoU
+ModelPredictiveControl.init_ZtoU
 ModelPredictiveControl.init_predmat
 ModelPredictiveControl.init_defectmat
 ModelPredictiveControl.relaxU

src/controller/construct.jl

@@ -844,7 +844,7 @@ Augment manipulated inputs constraints with slack variable ϵ for softening.
 Denoting the input increments augmented with the slack variable
 ``\mathbf{ΔŨ} = [\begin{smallmatrix} \mathbf{ΔU} \\ ϵ \end{smallmatrix}]``, it returns the
 augmented conversion matrix ``\mathbf{S̃}``, similar to the one described at
-[`init_ΔUtoU`](@ref). It also returns the ``\mathbf{A}`` matrices for the inequality
+[`init_ZtoU`](@ref). It also returns the ``\mathbf{A}`` matrices for the inequality
 constraints:
 ```math
 \begin{bmatrix}