doc: adding link to block diagram in other pages

Author: franckgaga

docs/src/public/predictive_control.md

@@ -1,4 +1,4 @@
-# Functions: Predictive Controllers
+# [Functions: Predictive Controllers](@id func_predictive_control)
 
 ```@contents
 Pages = ["predictive_control.md"]

docs/src/public/sim_model.md

@@ -15,7 +15,9 @@ method to manually modify them.
     The nomenclature in this page introduces the model manipulated input ``\mathbf{u}``,
     measured disturbances ``\mathbf{d}``, state ``\mathbf{x}`` and output ``\mathbf{y}``,
     four vectors of `nu`, `nd`, `nx` and `ny` elements, respectively. The ``\mathbf{s}``
-    vector combines the elements of ``\mathbf{u}`` and ``\mathbf{d}``.
+    vector combines the elements of ``\mathbf{u}`` and ``\mathbf{d}``. See the page
+    [Function: Predictive Controllers](@ref func_predictive_control) for a block diagram
+    overview.
 
 ## SimModel
 

docs/src/public/state_estim.md

@@ -31,7 +31,9 @@ solving the MPC problem with [`moveinput!`](@ref), for when the estimations are
     The nomenclature in this page introduces the estimated state ``\mathbf{x̂}`` and output
     ``\mathbf{ŷ}`` vectors of respectively `nx̂` and `ny` elements. Also, all the estimators
     support measured ``\mathbf{y^m}`` (`nym` elements) and unmeasured ``\mathbf{y^u}``
-    (`nyu` elements) model output, where ``\mathbf{y}`` refers to all of them.
+    (`nyu` elements) model output, where ``\mathbf{y}`` refers to all of them. See the page
+    [Function: Predictive Controllers](@ref func_predictive_control) for a block diagram
+    overview.
 
 ## StateEstimator