include "link" in "Wells for Boys" linkpost slug

Ordinarily I would go to great lengths to avoid breaking links by
changing slugs without a redirect solution, but who links to a filler
linkpost? Nobody! Nobody in the whole blogosphere has linked to this!

diff --git a/content/2020/wells-for-boys.md b/content/2020/link-wells-for-boys.md
similarity index 100%
rename from content/2020/wells-for-boys.md
rename to content/2020/link-wells-for-boys.md