fix(docs): fix spelling

[ko2in]

Fix spelling error instertion which should be insertion.

[codecov]

Codecov Report

Merging #716 (8ecee30) into master (6ae4c3e) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #716   +/-   ##
=======================================
  Coverage   89.67%   89.67%           
=======================================
  Files           6        6           
  Lines         775      775           
  Branches      239      239           
=======================================
  Hits          695      695           
  Misses         77       77           
  Partials        3        3           

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[alexander-akait]

Fixed #752