Documentation to mention additonal config if using gzip plugin

[edslocombe]

Love the plugin and the rest of ember-cli-deploy - thank you.

I just ran into an issue where my index.json file was gzipped along with other resources which obviously caused problems.

I don't believe this to be a bug but maybe worth adding to the docs / readme that if using in conjunction with ember-cli-deploy-gzip that you should add the following to your deploy.js file:

gzip: {
  ignorePattern: 'index.json'
}

[achambers]

Hi @edslocombe. Thanks for this. Fancy submitting s PR for the change?