Unify code block style in README
Unify code block style in README

Consistently use triple backtick syntax for code blocks.

Change-Id: I924fbc24c21671fc2ae8affb2aade1245f35e34e
Reviewed-on: https://gerrit.causes.com/32591
Tested-by: jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@causes.com>
Reviewed-by: Shane da Silva <6f6e68d1df92f30cb4b3ce35260ddf94a402f33d@causes.com>

artemartemov/scss-lint-hdm