add SDSS spectra notebook

[dougbrn]

This PR adds a lightweight tutorial/example of using nested-pandas with SDSS spectra.

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Before [71ae3ba] <v0.1.3>	After [660726d]	Ratio	Benchmark (Parameter)
33.1±0.9ms	35.3±3ms	1.07	benchmarks.AssignSingleDfToNestedSeries.time_run
57.8±2ms	60.6±4ms	1.05	benchmarks.ReassignHalfOfNestedSeries.time_run
9.37±0.2ms	9.56±0.3ms	1.02	benchmarks.NestedFrameAddNested.time_run
1.11±0.01ms	1.11±0.05ms	1.01	benchmarks.NestedFrameReduce.time_run
87.1M	87M	1	benchmarks.NestedFrameAddNested.peakmem_run
94.2M	93.9M	1	benchmarks.NestedFrameQuery.peakmem_run
90.7M	90.6M	1	benchmarks.NestedFrameReduce.peakmem_run
263M	260M	0.99	benchmarks.AssignSingleDfToNestedSeries.peakmem_run
281M	279M	0.99	benchmarks.ReassignHalfOfNestedSeries.peakmem_run
6.66±0.1ms	6.52±0.1ms	0.98	benchmarks.NestedFrameQuery.time_run

Click here to view all benchmarks.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.44%. Comparing base (71ae3ba) to head (d05af73).
Report is 72 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #134   +/-   ##
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  Coverage   99.44%   99.44%           
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  Files          14       14           
  Lines         897      897           
=======================================
  Hits          892      892           
  Misses          5        5           

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