LRDOCS-327 resources importer

Hi Jesse. The first commit is wordsmithing. The second commit breaks down how to each resource type from Liferay. The third provides an outline of steps the developer can use in developing their theme with its resources.

Let me know what you think. I think the content in the last two commits is good, but I'll understand if you think it would be better to "paragraph" one or both of them.