chore: fix website URL for Less

[sosukesuzuki]

Which issue # if any, does this resolve?

Please check one:

• New tests created for this change
• Tests updated for this change

This PR:

• Adds new API
• Extends existing API, backwards-compatible
• Introduces a breaking change
• Fixes a bug

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Just fix URL for Less in README.md.

[codecov-commenter]

Codecov Report

Merging #162 (3cbb17d) into master (5a4a4ac) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #162   +/-   ##
=======================================
  Coverage   97.38%   97.38%           
=======================================
  Files           3        3           
  Lines         153      153           
=======================================
  Hits          149      149           
  Misses          4        4           

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[shellscape]

Thanks