Document Lopez Crawl Directives (on the Wiki)

[tokahuke]

This is a tracking issue for the (current inexistent) documentation on Lopez Crawler Directives.

Basically, if you just landed here, by now, you just need to explain the module lib-lopez/src/directives to the layman.

[tokahuke]

I have taken a day off work. This seems to have advanced a great deal already. However, there are still some points missing from the docs, namely:

• Documenting the use params and ignore params directives for controlling URL queries.
• A guide to the (small-ish) CLI. Maybe this is redundant with the Quickstart.