Refit models models and reduce file size - #1

- Split LICENSE into a DCF stub plus LICENSE.md with the full MIT
  text, matching BirdFlowR's convention (required for
  License: MIT + file LICENSE).
- Drop the dead Remotes: birdflow-science/BirdFlowR line; nothing in
  Imports/Depends needs it.
- Title-case the DESCRIPTION Title field.
- Regenerate roxygen docs under the BirdFlowExamples name.
- Fix a doc typo (polyon -> polygon) and update inst/WORDLIST for the
  current data citation.
- Add a NEWS.md entry for the rename and refit.

Documents the ~6.3MB installed size, which exceeds the informal
5MB CRAN guideline, and why: amewoo/rewbla are already fit at
coarse resolution with heavy sparsification to minimize size
while still exercising their intended code paths.