#489 Replace Russell's Theorem with a better main example

[Nathan Carter]

We use Russell's Theorem a lot on our website and in the Lurch topics list itself. But after this semester, Ken has accumulated a lot of good examples of interesting theorems proven in Lurch, and should wade through that collection to find a better example to use in place of Russell. Then replace Russell with that example in as many publicly visible places as possible. Alternately, if several good examples were found, they could each be used in a different publicly visible location.