Fix a typo.

Summary: The `lessc` binary is a part of the NPM `less` module.

Test Plan: `npm install less` works whereas `npm install lessc` does not.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9006

src/lint/linter/ArcanistLesscLinter.php

@@ -59,7 +59,7 @@ final class ArcanistLesscLinter extends ArcanistExternalLinter {
   }
 
   public function getInstallInstructions() {
-    return pht('Install lessc using `npm install -g lessc`.');
+    return pht('Install lessc using `npm install -g less`.');
   }
 
   public function shouldExpectCommandErrors() {