"grunt patternlab:build" task does not do anything

[greenc]

Expected Behavior

Running grunt patternlab:build generates the front-end of Pattern Lab

Actual Behavior

Running grunt patternlab:build does nothing (except output the help text)

Steps to Reproduce

• Delete the public/ directory
• Run grunt patternlab:build task
• Verify that public/ directory has not been created/populated

Steps to Fix

Should just be a case of adding the task alias to Grunt. PR incoming.