Added static DOI to README.md, updated text in ROOT_Model section

README.md
- Now points to static DOI https://doi.org/10.5281/zenodo.6563908,
  which will always point to the latest KPP version

docs/source/using_kpp/05_output_from_kpp.rst
- Reworded paragraph about how ROOT_Model unifies all modules
  for easy inclusion into F90 programs

Signed-off-by: Bob Yantosca <yantosca@seas.harvard.edu>

README.md

@@ -1,4 +1,7 @@
-[![Latest Release](https://img.shields.io/github/v/release/KineticPreProcessor/KPP?label=Latest%20Release)](https://kpp.readthedocs.io) [![License: GPL v3](https://img.shields.io/badge/License-GPLv3-blue.svg)](https://github.com/KineticPreProcessor/KPP/blob/main/LICENSE.txt) [![C-I tests](https://img.shields.io/azure-devops/build/KineticPreProcessor/KPP/1/main?label=C-I%20Tests)](https://dev.azure.com/KineticPreProcessor/KPP/_build) [![ReadTheDocs](https://assets.readthedocs.org/static/projects/badges/passing-flat.svg)](https://kpp.readthedocs.io/en/latest)
+[![Latest
+Release](https://img.shields.io/github/v/release/KineticPreProcessor/KPP?label=Latest%20Release)](https://kpp.readthedocs.io) [![License: GPL
+v3](https://img.shields.io/badge/License-GPLv3-blue.svg)](https://github.com/KineticPreProcessor/KPP/blob/main/LICENSE.txt) [![C-I
+tests](https://img.shields.io/azure-devops/build/KineticPreProcessor/KPP/1/main?label=C-I%20Tests)](https://dev.azure.com/KineticPreProcessor/KPP/_build) [![ReadTheDocs](https://assets.readthedocs.org/static/projects/badges/passing-flat.svg)](https://kpp.readthedocs.io/en/latest) [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.6563908.svg)](https://doi.org/10.5281/zenodo.6563908)
 
 # The Kinetic PreProcessor: KPP
 This is the repository for the The Kinetic PreProcessor (KPP) source code.

docs/source/using_kpp/05_output_from_kpp.rst

@@ -64,8 +64,9 @@ Using :command:`#DRIVER none` will skip generating this file.
 ROOT_Model
 ----------
 
-The file :file:`ROOT_Model.f90` (or :file:`.F90`) completely
-defines the model by using all the associated modules.
+The file :file:`ROOT_Model.f90` (or :file:`.F90`) unifies all model
+definitions in a single module. This simplifies inclusion into
+external Fortran programs.
 
 .. _Initialize:
 
@@ -172,9 +173,7 @@ ROOT_Parameters
 
 The global parameters listed in :ref:`table-par` are defined and
 initialized in :file:`ROOT_Parameters.f90` (or
-:file:`.F90`).  The values listed in the third column
-of Table 4 are taken from the :command:`small_strato` example mechanism,
-which is described in :ref:`running-kpp-with-an-example-mechanism`.
+:file:`.F90`). 
 
 .. _table-par:
 
@@ -207,6 +206,10 @@ which is described in :ref:`running-kpp-with-an-example-mechanism`.
    | :code:`indf_spc`   | Index of fixed species *spc* in :code:`FIX` |        |
    +--------------------+---------------------------------------------+--------+
 
+   NOTE: Values listed the 3rd column of Table 5  are from the
+   :command:`small_strato` mechanism
+   (cf. :ref:`running-kpp-with-an-example-mechanism`). 
+
 KPP orders the variable species such that the sparsity pattern of the
 Jacobian is maintained after an LU decomposition. For our example there
 are five variable species (:code:`NVAR = 5`) ordered as