Bump mustache from 0.4.0 to 2.2.1 in /docs/slides/plpv14/_support/reveal

Bumps [mustache](https://github.com/janl/mustache.js) from 0.4.0 to 2.2.1.
- [Release notes](https://github.com/janl/mustache.js/releases)
- [Changelog](https://github.com/janl/mustache.js/blob/master/CHANGELOG.md)
- [Commits](janl/mustache.js@0.4.0...v2.2.1)

---
updated-dependencies:
- dependency-name: mustache
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

docs/slides/plpv14/_support/reveal/package.json

@@ -14,7 +14,7 @@
 		"underscore" : "1.3.3",
 		"express" : "2.5.9",
 		"socket.io" : "0.9.6",
-		"mustache" : "0.4.0"
+		"mustache" : "2.2.1"
 	},
 	"devDependencies": {}
 }