Standardize libpysal/examples/*.py docstrings

[jGaboardi]

See #290

This PR adds type hints and standardizes the following docstrings:

• libpysal/examples/__init__.py
• libpysal/examples/base.py
• libpysal/examples/builtin.py
• libpysal/examples/remotes.py

[codecov]

Codecov Report

Merging #294 into master will increase coverage by 0.00%.
The diff coverage is 64.77%.

@@           Coverage Diff           @@
##           master     #294   +/-   ##
=======================================
  Coverage   81.12%   81.13%           
=======================================
  Files         115      115           
  Lines       11674    11679    +5     
=======================================
+ Hits         9471     9476    +5     
  Misses       2203     2203           

Impacted Files	Coverage Δ
libpysal/examples/remotes.py	83.56% <ø> (ø)
libpysal/examples/base.py	53.02% <45.94%> (+0.31%)	⬆️
libpysal/common.py	82.69% <55.55%> (+0.33%)	⬆️
libpysal/cg/ops/_accessors.py	80.00% <75.00%> (ø)
libpysal/cg/voronoi.py	79.00% <80.00%> (+0.42%)	⬆️
libpysal/examples/builtin.py	89.74% <85.71%> (ø)
libpysal/examples/__init__.py	90.90% <100.00%> (+0.43%)	⬆️

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[jGaboardi]

Revisit after @slumnitz's catch.

[jGaboardi]

Currently failing with:

requests.exceptions.MissingSchema: Invalid URL 'data/ncovr.zip': No schema supplied. Perhaps you meant http://data/ncovr.zip?

[sjsrey]

Currently failing with:

requests.exceptions.MissingSchema: Invalid URL 'data/ncovr.zip': No schema supplied. Perhaps you meant http://data/ncovr.zip?

Chicago relocated the example data to GitHub so our crawler has to be updated. See #295