Rearrange basic documentation

[jeremykubica]

Rearrange the documentation to breakout installation and example usage.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.47%. Comparing base (31127f5) to head (b09a1e1).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #793   +/-   ##
=======================================
  Coverage   92.47%   92.47%           
=======================================
  Files          71       71           
  Lines        6739     6739           
=======================================
  Hits         6232     6232           
  Misses        507      507           

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[github-actions]

Before [31127f5]	After [488dd65]	Ratio	Benchmark (Parameter)
2.04±0.4ms	1.67±0.5ms	~0.82	benchmarks.TimeSuite.time_evaluate_simple_linear_wavelength_model
24.9±0.4ms	27.1±2ms	1.09	benchmarks.TimeSuite.time_chained_evaluate_sed
12.0±0.7ms	12.9±0.7ms	1.07	benchmarks.TimeSuite.time_evaluate_salt3_model
1.13±0.06ms	1.20±0.1ms	1.07	benchmarks.TimeSuite.time_fnu_to_flam
6.61±0.1ms	6.92±0.08ms	1.05	benchmarks.TimeSuite.time_evaluate_salt3_passbands
9.20±0.2ms	9.44±0.07ms	1.03	benchmarks.TimeSuite.time_apply_white_noise
41.2±0.2μs	42.5±0.7μs	1.03	benchmarks.TimeSuite.time_make_new_salt3_model
10.4±0.1ms	10.6±0.2ms	1.02	benchmarks.TimeSuite.time_load_passbands
29.3±0.2μs	29.8±0.6μs	1.02	benchmarks.TimeSuite.time_make_simple_linear_wavelength_model
5.65±0.06ms	5.69±0.06ms	1.01	benchmarks.TimeSuite.time_lightcurve_source

Click here to view all benchmarks.