Add initial documentation for IncludeCancellationParameter

[sharwell]

Fixes #44

[codecov]

Codecov Report

Merging #71 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #71   +/-   ##
=======================================
  Coverage   81.26%   81.26%           
=======================================
  Files          38       38           
  Lines        2856     2856           
  Branches      184      184           
=======================================
  Hits         2321     2321           
  Misses        440      440           
  Partials       95       95

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