Document required browserify option "dedupe: false"

[kumavis]

trafficstars

also:

• some additional comments
• example code sets { dedupe: false }
• example code triggers dedupe
• update browserify to version that allows setting dedupe: false

Fixes/Updates https://github.com/browserify/factor-bundle/issues/51

[kumavis]

cc @goto-bus-stop @ljharb thanks/