nvim: Fix bibcite insertion position

Fixed the position of my BibTex citations to be in front of the cursor
not appended to it (i.e. using `i` instead of `a`).

That means for example `sometext <insertioninvoked>.` will put the
insertion *before* the full stop instead of after it, which was kind of
weird.

nvim/.config/nvim/spell/en.utf-8.add

@@ -98,3 +98,4 @@ weaponization
 blog
 flexicurity
 indices
+Anthropocene