remove height spec from logo

Author: wholmgren

README.md

@@ -1,4 +1,4 @@
-<img src="docs/sphinx/source/_images/pvlib_logo_horiz.png" width="600" height="260">
+<img src="docs/sphinx/source/_images/pvlib_logo_horiz.png" width="600">
 
 [![TravisCI](https://travis-ci.org/pvlib/pvlib-python.svg?branch=master)](https://travis-ci.org/pvlib/pvlib-python)
 [![Build status](https://ci.appveyor.com/api/projects/status/gr2eyhc84tvtkopk?svg=true)](https://ci.appveyor.com/project/wholmgren/pvlib-python-fv2to)
@@ -82,4 +82,4 @@ If you use pvlib-python in a published work, please cite:
 
 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)
+[Zenodo.org](https://zenodo.org/search?page=1&size=20&q=conceptrecid:593284&all_versions&sort=-version)