docs: fix a typo in plugins page.

docs: fix a typo in plugins page.
change 'chroma' to 'chrome'
Merge pull request #726 from tychio/patch-1

docs: fix a typo in plugins page.
docs(migration): module.export/module.exports

Change code snippet to use module.exports rather than module.export, because that's what the runner expects, and previous sample code doesn't work from copy-paste.
Merge pull request #766 from psyked/patch-3

docs(migration): module.export/module.exports