DOC: Add best practice for loading data

[aresnow1]

What do these changes do?

Add best practice for loading data.

Related issue number

Fixes #376

Check code requirements

• [ ] tests added / passed (if needed)
• [ ] Ensure all linting tests pass

[codecov[bot]]

Codecov Report

Merging #620 (cb111bb) into main (4e1a5a2) will increase coverage by 14.32%. The diff coverage is n/a.

@@             Coverage Diff             @@
##             main     #620       +/-   ##
===========================================
+ Coverage   79.23%   93.56%   +14.32%     
===========================================
  Files        1020     1020               
  Lines       79032    79032               
  Branches    16393    16393               
===========================================
+ Hits        62624    73946    +11322     
+ Misses      14611     3417    -11194     
+ Partials     1797     1669      -128     

Flag	Coverage Δ
unittests	93.46% <ø> (+14.24%)	:arrow_up:

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see 268 files with indirect coverage changes