add testing status badge (#50)

Author: zingale

README.md

@@ -1,4 +1,6 @@
 [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.13356324.svg)](https://doi.org/10.5281/zenodo.13356324)
+[![PyPI Version](https://img.shields.io/pypi/v/ppmpy)](https://pypi.org/project/ppmpy)
+[![pytest-all](https://github.com/python-hydro/ppmpy/actions/workflows/pytest-all.yml/badge.svg)](https://github.com/python-hydro/ppmpy/actions/workflows/pytest-all.yml)
 
 # PPMpy
 
@@ -7,11 +9,19 @@ visualization of the steps in mind.
 
 ## Installation
 
+From PyPI:
+
 ```
-pip install .
+pip install ppmpy
 ```
 
+From source:
+
+```
+pip install .
+```
 
 ## Running
 
-see the examples in `ppmpy/examples/`
+See the documentation at: https://python-hydro.github.io/ppmpy/intro.html
+for usage examples.