add "powered by pvlib" logos (#1277)

* add powered logos

* change README, whatsnew

* add powered by logos, license to docs

* blank line

* link formatting

* move logos to citing. move citing up, license down

* one line for less vert space

* typo

Co-authored-by: Will Holmgren <william.holmgren@gmail.com>

Author: cwhanse

README.md

@@ -111,11 +111,24 @@ Please see the [Contributing page](http://pvlib-python.readthedocs.io/en/stable/
 The long-term success of pvlib-python requires substantial community support.
 
 
-License
-=======
+Citing
+======
+
+If you use pvlib-python in a published work, please cite:
+
+  William F. Holmgren, Clifford W. Hansen, and Mark A. Mikofski.
+  "pvlib python: a python package for modeling solar energy systems."
+  Journal of Open Source Software, 3(29), 884, (2018).
+  https://doi.org/10.21105/joss.00884
 
-BSD 3-clause
+Please also cite the DOI corresponding to the specific version of
+pvlib-python that you used. pvlib-python DOIs are listed at
+[Zenodo.org](https://zenodo.org/search?page=1&size=20&q=conceptrecid:593284&all_versions&sort=-version)
 
+If you use pvlib-python in a commercial or publicly-available application, please
+consider displaying one of the "powered by pvlib" logos:
+
+<img src="docs/sphinx/source/_images/pvlib_powered_logo_vert.png" width="300"><img src="docs/sphinx/source/_images/pvlib_powered_logo_horiz.png" width="300">
 
 Getting support
 ===============
@@ -133,19 +146,12 @@ change something about pvlib, then please make an issue on our
 [GitHub issues page](https://github.com/pvlib/pvlib-python/issues).
 
 
-Citing
-======
 
-If you use pvlib-python in a published work, please cite:
+License
+=======
 
-  William F. Holmgren, Clifford W. Hansen, and Mark A. Mikofski.
-  "pvlib python: a python package for modeling solar energy systems."
-  Journal of Open Source Software, 3(29), 884, (2018).
-  https://doi.org/10.21105/joss.00884
+BSD 3-clause.
 
-Please also cite the DOI corresponding to the specific version of
-pvlib-python that you used. pvlib-python DOIs are listed at
-[Zenodo.org](https://zenodo.org/search?page=1&size=20&q=conceptrecid:593284&all_versions&sort=-version)
 
 NumFOCUS
 ========

docs/sphinx/source/_images/pvlib_powered_logo_horiz.png

@@ -9,8 +9,7 @@ functions and classes for simulating the performance of photovoltaic
 energy systems. pvlib python was originally ported from the PVLIB MATLAB
 toolbox developed at Sandia National Laboratories and it implements many
 of the models and methods developed at the Labs. More information on
-Sandia Labs PV performance modeling programs can be found at
-https://pvpmc.sandia.gov/. We collaborate with the PVLIB MATLAB project,
+Sandia Labs PV performance modeling programs can be found at the `PVPMC <https://pvpmc.sandia.gov/>`_. We collaborate with the PVLIB MATLAB project,
 but operate independently of it.
 
 The source code for pvlib python is hosted on `github
@@ -50,6 +49,16 @@ Please also cite the DOI corresponding to the specific version of
 pvlib python that you used. pvlib python DOIs are listed at
 `Zenodo.org <https://zenodo.org/search?page=1&size=20&q=conceptrecid:593284&all_versions&sort=-version>`_
 
+If you use pvlib-python in a commercial or publicly-available
+application, please consider displaying one of the "powered by pvlib"
+logos:
+
+.. image:: _images/pvlib_powered_logo_horiz.png
+  :width: 300
+
+.. image:: _images/pvlib_powered_logo_vert.png
+  :width: 300
+
 Additional pvlib python publications include:
 
 * J. S. Stein, “The photovoltaic performance modeling
@@ -73,6 +82,10 @@ Additional pvlib python publications include:
   "An Open Source Solar Power Forecasting Tool Using PVLIB-Python,"
   in 43rd Photovoltaic Specialists Conference, 2016.
 
+License
+=======
+
+`BSD 3-clause <https://github.com/pvlib/pvlib-python/LICENSE>`_.
 
 NumFOCUS
 ========
@@ -83,7 +96,6 @@ pvlib python is a `NumFOCUS Affiliated Project <https://numfocus.org/sponsored-p
   :target: https://numfocus.org/sponsored-projects/affiliated-projects
   :alt: NumFocus Affliated Projects
 
-
 Contents
 ========
 

docs/sphinx/source/_images/pvlib_powered_logo_vert.png

@@ -226,6 +226,7 @@ Documentation
 * Clarified how statistics are calculated for :py:func:`pvlib.clearsky.detect_clearsky`
   (:issue:`1070`, :pull:`1243`)
 * Add gallery examples using the new ``Mount`` classes (:pull:`1266`)
+* Add "powered by pvlib" logos (:pull:`1277`)
 
 Requirements
 ~~~~~~~~~~~~