Delete the first paragraph of LICENSE-MIT (an inaccurate
pseudo-copyright line), leaving only the text of the MIT license.

Nothing about the license of proc-macro2 has changed, only our
understanding of how to correctly communicate that license has changed.

This mirrors an equivalent change applied in the rust-lang/rust
repository years ago.

GitHub's default timeout is 6 hours. Recently some of my GitHub Actions
jobs have started randomly stalling for that long, which is inconvenient
because it ties up a chunk of my runner quota. It apepars to be very
rare for a job to recover after stalling. It's better to time out
quicker and retry on a different runner.

I'd like a chance to audit all the code that rustdoc is inserting into
the docs. Currently I am skeptical that showing proc-macro2's internal
usages of APIs is a net benefit to the public documentation. I am also
skeptical that quite so many examples are needed, and that they should
be featured so prominently in comparison to handwritten docs. Lastly I
wish there were a way to turn this behavior off on a more granular
basis.