Update docs to remove dead links to old Google code source

[belugabehr]

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[jrottinghuis]

Thanks for finding broken link @belugabehr. I agree we should update this.
It seems reasonable to keep some reference to the origins of this code though, to make it clear it was a fork.
Rather than completely abandoning this section, I think it makes sense to link it to what appears to be the new location for the archive of the original: https://code.google.com/archive/a/apache-extras.org/p/hadoop-gpl-compression/wikis/FAQ.wiki

Note that the link to the Cloudera blog is broken as well. I think we can simply drop that paragraph of how Twitter uses hadoop-lzo altogether.

I think it is fair to drop the "To get started" paragraph as you did in this PR.