Add basic docs for plot module

docs/index.rst

@@ -19,6 +19,7 @@ You can find the code in the ``hera_pspec`` `GitHub repository <https://github.c
    pspecdata
    uvpspec
    container
+   plot
 
 
 Indices and tables

docs/plot.rst

@@ -0,0 +1,37 @@
+Simple plotting functions
+=========================
+
+The ``hera_pspec.plot`` module contains functions for making simple plots of delay power spectra.
+
+A simple example 
+
+.. code-block:: python
+  
+  # Load or generate a UVPSpec object containing delay power spectra
+  uvp = ...
+  
+  # Set which baseline-pairs should be included in the plot
+  blpairs = list(uvp.blpair_array) # This includes all blpairs!
+  
+  # Plot the delay spectrum, averaged over all blpairs and times
+  # (for the spectral window with index=0, and polarization 'xx')
+  ax = hp.plot.delay_spectrum(uvp, [blpairs,], spw=0, pol='xx', 
+                              average_blpairs=True, average_times=True, 
+                              delay=False)
+  
+  # Setting delay=False plots the power spectrum in cosmological units
+  
+For a more extensive worked example, see `this example Jupyter notebook <https://github.com/HERA-Team/hera_pspec/blob/master/examples/Plotting_examples.ipynb>`_.
+
+.. contents::
+  :local:
+
+
+Plot module
+-----------
+
+The only plotting function currently available in the `hera_pspec.plot` module is `delay_spectrum()`.
+
+.. automodule:: hera_pspec.plot
+  :members:
+