add code references to gas solid contactors docs (#1451)

Co-authored-by: Ludovico Bianchi <lbianchi@lbl.gov>

docs/reference_guides/model_libraries/gas_solid_contactors/flowsheets/dyn_TGA_example.rst

@@ -7,6 +7,15 @@ Dynamic flowsheet example of the fixed bed 0D model for thermogravimetric analys
 
 This model is for demonstration and tutorial purposes only.
 
+The model code is located in the `main flowsheet module <https://github.com/IDAES/idaes-pse/blob/main/idaes/models_extra/gas_solid_contactors/flowsheets/dyn_TGA_example.py>`_ and may be imported as:
+
+.. code:: python
+
+  >>> from pyomo.environ import ConcreteModel
+  >>> from idaes.models_extra.gas_solid_contactors.flowsheets.dyn_TGA_example import main
+  >>> m = ConcreteModel()
+  >>> m = main(m)
+
 Inputs:
 
 * Gas feed  - flowrate, pressure, temperature, composition

docs/reference_guides/model_libraries/gas_solid_contactors/flowsheets/ss_BFB_OC_oxidation.rst

@@ -7,6 +7,13 @@ Steady-state flowsheet example of the bubbling fluidized bed model for oxidation
 
 This model is for demonstration and tutorial purposes only.
 
+The model code is located in the `main flowsheet module <https://github.com/IDAES/idaes-pse/blob/main/idaes/models_extra/gas_solid_contactors/flowsheets/ss_BFB_OC_oxidation.py>`_ and may be imported as:
+
+.. code:: python
+
+  >>> from idaes.models_extra.gas_solid_contactors.flowsheets.ss_BFB_OC_oxidation import main
+  >>> m = main()
+
 Inputs:
 
 * Bed diameter

docs/reference_guides/model_libraries/gas_solid_contactors/flowsheets/ss_BFB_methane_combustion.rst

@@ -7,6 +7,13 @@ Steady-state flowsheet example of the bubbling fluidized bed model for methane c
 
 This model is for demonstration and tutorial purposes only.
 
+The model code is located in the `main flowsheet module <https://github.com/IDAES/idaes-pse/blob/main/idaes/models_extra/gas_solid_contactors/flowsheets/ss_BFB_methane_combustion.py>`_ and may be imported as:
+
+.. code:: python
+
+  >>> from idaes.models_extra.gas_solid_contactors.flowsheets.ss_BFB_methane_combustion import main
+  >>> m = main()
+
 Inputs:
 
 * Bed diameter

docs/reference_guides/model_libraries/gas_solid_contactors/flowsheets/ss_MB_methane_combustion.rst

@@ -7,6 +7,13 @@ Steady-state flowsheet example of the moving bed reactor model for methane combu
 
 This model is for demonstration and tutorial purposes only.
 
+The model code is located in the `main flowsheet module <https://github.com/IDAES/idaes-pse/blob/main/idaes/models_extra/gas_solid_contactors/flowsheets/ss_MB_methane_combustion.py>`_ and may be imported as:
+
+.. code:: python
+
+  >>> from idaes.models_extra.gas_solid_contactors.flowsheets.ss_MB_methane_combustion import main
+  >>> m = main()
+
 Inputs:
 
 * Bed diameter

docs/reference_guides/model_libraries/gas_solid_contactors/unit_models/bubbling_fluidized_bed.rst

@@ -7,6 +7,12 @@ The BFBR model is represented as a 1-D axially discretized model with two phases
 and two regions (bubble and emulsion). The model captures the gas-solid interaction between both phases and regions 
 through reaction, mass and heat transfer.
 
+The model code is located in the `main unit model module <https://github.com/IDAES/idaes-pse/blob/main/idaes/models_extra/gas_solid_contactors/unit_models/bubbling_fluidized_bed.py>`_ and may be imported as:
+
+.. code:: python
+
+  >>> from idaes.models_extra.gas_solid_contactors.unit_models.bubbling_fluidized_bed import BubblingFluidizedBed
+
 **Assumptions:**
 
 * Cloud-wake region effects are negligible and are not modelled.

docs/reference_guides/model_libraries/gas_solid_contactors/unit_models/fixed_bed_0D.rst

@@ -6,6 +6,12 @@ solid phase bed.
 The FixedBed0D mathematical model is a 0-D time variant model with two phases (gas and solid). The model captures the
 gas-solid interaction between both phases through reaction, mass and heat transfer.
 
+The model code is located in the `main unit model module <https://github.com/IDAES/idaes-pse/blob/main/idaes/models_extra/gas_solid_contactors/unit_models/fixed_bed_0D.py>`_ and may be imported as:
+
+.. code:: python
+
+  >>> from idaes.models_extra.gas_solid_contactors.unit_models.fixed_bed_0D import FixedBed0D
+
 **Assumptions:**
 
 * There is assumed to be no axial or radial variation in solid composition. 

docs/reference_guides/model_libraries/gas_solid_contactors/unit_models/fixed_bed_1D.rst

@@ -4,7 +4,13 @@ Fixed Bed 1D Reactor
 The IDAES Fixed Bed 1D Reactor (FixedBed1D) model represents a unit operation where a gas stream  
 passes through a solid phase bed in a linear reactor vessel.
 The FixedBed1D mathematical model is a 1-D time variant model with two phases (gas and solid). The model captures the
-gas-solid interaction between both phases through reaction/adsorption, mass and heat transfer. 
+gas-solid interaction between both phases through reaction/adsorption, mass and heat transfer.
+
+The model code is located in the `main unit model module <https://github.com/IDAES/idaes-pse/blob/main/idaes/models_extra/gas_solid_contactors/unit_models/fixed_bed_1D.py>`_ and may be imported as:
+
+.. code:: python
+
+  >>> from idaes.models_extra.gas_solid_contactors.unit_models.fixed_bed_1D import FixedBed1D
 
 **Assumptions:**
 

docs/reference_guides/model_libraries/gas_solid_contactors/unit_models/moving_bed.rst

@@ -5,7 +5,13 @@ The IDAES Moving Bed Reactor (MBR) model represents a unit operation where two m
 solid phase and a gas phase – pass through a linear reactor vessel while undergoing chemical reaction(s). 
 The two streams have opposite flow directions (counter-flow).
 The MBR mathematical model is a 1-D rigorous first-principles model consisting of a set of differential 
-equations obtained by applying the mass, energy (for each phase) and momentum balance equations. 
+equations obtained by applying the mass, energy (for each phase) and momentum balance equations.
+
+The model code is located in the `main unit model module <https://github.com/IDAES/idaes-pse/blob/main/idaes/models_extra/gas_solid_contactors/unit_models/moving_bed.py>`_ and may be imported as:
+
+.. code:: python
+
+  >>> from idaes.models_extra.gas_solid_contactors.unit_models.moving_bed import MBR
 
 **Assumptions:**