Update the blob worker docs with an example webpack config file.

Shouldn't be necessary to do multiple webpack runs with this configuration.

@andywer What do you think of this PR? Anything I can do to make it more palatable?

Great stuff! Thanks, @pkerpedjiev!

Unfortunately I didn't find the time to review any earlier. Could you also provide a test case (we have a few tests that build using webpack and then run the result)?

I haven't tested it yet. Are you actively using this approach?
Otherwise totally happy to merge it 🙂