Article text chunker shouldn't pick sentences like "References"

[earwig]

https://copyvios.toolforge.org/?lang=en&project=wikipedia&oldid=1345145912&action=search&use_engine=1&use_links=1

There's probably some information-theoretic thing we can do here to be clever and discard sentences that seem too common, but even a very rough approximation of that built by blacklisting common section titles would be valuable to start with.