As every proper repo, the min file should be already included. Don't expect every dev can build it (might use win and missing some build tools).

Put the min file in this folder '/dist' and can be named 'bitcoinjs-lib.min.js'.

Edit: Seems like you have already talked about this: #252 but you closed. I have to say that I've never found a bower component that requires any build step before use. Take a look at every client side javascript lib (not only bower) and you will see that they all have a min file bundled. You can create a script to run every time you want to publish a new version that creates the min file and do other stuff you need.

If you don't put a min file then many client side dev will not use this (I don't know if you care or not, but I hope you do).