If writeable is OK, so is overwriteable

Both should probably appear in the en-GB_to_en-USdictionary instead of
the standard dictionary.

codespell_lib/data/dictionary.txt

@@ -42354,7 +42354,6 @@ overwridden->overridden, overwritten,
 overwride->overwrite, override,
 overwrides->overwrites, overrides,
 overwriding->overwriting, overriding,
-overwriteable->overwritable
 overwrited->overwritten, overwrote,
 overwriten->overwritten
 overwritin->overwriting