message: Add a missing "and" in ufmt/README.md
diff: **This is a fork of the [ufmt](https://github.com/japaric/ufmt) crate.** We are
  currently evaluating whether `libtock-rs` should use `ufmt` for its debug
  formatting functionality. Because `ufmt` has unfixed bugs (and appears to be
  -unmaintained), we have forked it here are making bugfixes.
  +unmaintained), we have forked it here and are making bugfixes.
  This fork is temporary and will be removed when one of the following happens:
  