Add example of data filtering to Logging docs

[npetersen2]

This issue was moved from the AMDC-Firmware repo: Severson-Group/AMDC-Firmware#144

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Per @Nick-Hemenway

You can VERY easily filter data in python pandas as follows:

First, create a filtering function:

# If the window length is 21, it will fit 10 data points to each side of the data point that is being smoothed
from scipy import signal
my_filter = lambda x: signal.savgol_filter(x, window_length = 21, polyorder = 2)

Then, to use the filter:

TODO

Since this is so easy and could be a very common thing to do when logging data, add a section to the Logging markdown docs with the above information.