Update README to reflect changes in refactor

Fixes #17
Fixes #27
Yes I say in the docs why.

> Block helper used to create a new `intl` data scope by updating the i18n data supplied to Handlebars within the block. This is useful when you need to render part of the page in a particular locale, or need to supply the i18n data to Handlebars via the template context — some Handlebars integrations might not support supplying `options.data.intl` when rendering.