Improve end-user guidance & developer examples

[casperdcl]

• update customcomplete with a complex use-case
• add helpful header (instructions to end-users) to generated scripts
• minor whitespace linting

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.52%. Comparing base (d74f60e) to head (cdc6094).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #253   +/-   ##
=======================================
  Coverage   87.52%   87.52%           
=======================================
  Files           3        3           
  Lines         489      489           
  Branches       95       95           
=======================================
  Hits          428      428           
  Misses         34       34           
  Partials       27       27           

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