add packages explicitly imported in example to notebook_requirements.txt

Even though some of these are also installed as requirments for RdTools, specific versions are now specified for the example.

README.md

@@ -60,7 +60,7 @@ RdTools currently runs in both Python 2.7 and 3.6.
 ## Usage and examples
 
 
-Full workflow examples are found in the notebooks in [rdtools/docs](./docs/degradation_example.ipynb). The examples are designed to work with python 3.6. For a consistent experience, we recommend installing the packages and versions documented in `docs/notebook_requirements.txt`. This can be achieved in your environment by running `pip install -r docs/notebook_requirements.txt` from the base directory. (RdTools must also be separately installed as described above.)
+Full workflow examples are found in the notebooks in [rdtools/docs](./docs/degradation_example.ipynb). The examples are designed to work with python 3.6. For a consistent experience, we recommend installing the packages and versions documented in `docs/notebook_requirements.txt`. This can be achieved in your environment by first installing RdTools as described above, then running `pip install -r docs/notebook_requirements.txt` from the base directory.
 
 The following functions are used for degradation analysis:
 

docs/notebook_requirements.txt

@@ -23,13 +23,16 @@ mistune==0.8.3
 nbconvert==5.3.1
 nbformat==4.4.0
 notebook==5.6.0
+numpy==1.15.2
+pandas==0.23.4
 pandocfilters==1.4.2
 parso==0.3.1
 pexpect==4.6.0
 pickleshare==0.7.4
 prometheus-client==0.3.0
 prompt-toolkit==1.0.15
 ptyprocess==0.6.0
+pvlib==0.5.2
 Pygments==2.2.0
 pyparsing==2.2.0
 pyzmq==17.1.0