docs: added controller class example

[dlhandsome]

Checklist

• npm test passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

None

Description of change

Added controller class example

[atian25]

should replace the exports, delete it

[codecov]

Codecov Report

Merging #20 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master    #20   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           3      3           
  Lines           9      9           
=====================================
  Hits            9      9

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[dlhandsome]

@atian25 done