Document some sample regexp ignores

[ivan]

Perhaps using the same examples as in the ArchiveBot docs

[Asparagirl]

+1 -- I am terrible at regex and this was always hard for me to do correctly with my own wpull runs or ArchiveBot.

[ethus3h]

I usually just go to http://pythex.org/ and figure it out by trial and error, that's a very useful tool for discovering them