Documentation update for v0.10

[jeandet]

Mostly a Documentation rewrite with the following notable changes:

• The documentation is split in two, one user doc written in rst files only and one API doc generated from docstrings
• The doc format used is numpydoc since it has a better rendering inside IPython terminal
• All examples except the one which require a login are tested on CI with doctest e72bb70

It also:

• drops python 3.6 support 69aa198
• adds python 3.10 support 69aa198
• deprecates and rename get_orbit from sscweb module to get_trajectory 52008a2, f2f4fb4
• adds citation file 904c824
• adds missing history entries for past releases 78453aa
• adds a notebook gallery a59831f with clickable examples code 450e6ed
• refactors notebooks examples a59831f and ce84a50

We should be able to release (0.10.0) now and continue improving documentation on each release.

[codecov]

Codecov Report

Merging #26 (1930377) into main (27b9e6c) will decrease coverage by 1.36%.
The diff coverage is 95.45%.

@@            Coverage Diff             @@
##             main      #26      +/-   ##
==========================================
- Coverage   86.91%   85.54%   -1.37%     
==========================================
  Files          31       31              
  Lines        1467     1474       +7     
  Branches      209      248      +39     
==========================================
- Hits         1275     1261      -14     
- Misses        130      150      +20     
- Partials       62       63       +1     

Flag	Coverage Δ
unittests	85.54% <95.45%> (-1.37%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
speasy/products/catalog.py	94.87% <ø> (ø)
speasy/products/dataset.py	96.96% <ø> (+9.09%)	⬆️
speasy/products/timetable.py	96.55% <ø> (ø)
speasy/products/variable.py	93.10% <ø> (+1.14%)	⬆️
speasy/webservices/amda/__init__.py	100.00% <ø> (ø)
speasy/webservices/amda/inventory.py	96.66% <ø> (ø)
speasy/webservices/ssc/__init__.py	85.71% <60.00%> (-2.35%)	⬇️
speasy/__init__.py	90.00% <100.00%> (ø)
speasy/config/__init__.py	95.55% <100.00%> (ø)
speasy/core/__init__.py	95.00% <100.00%> (-2.50%)	⬇️
... and 10 more

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[jeandet]

I've added #33 trivial fix commit to merge all at once.