Provide more alternatives

Co-authored-by: Peter Newman <peternewman@users.noreply.github.com>

Author: joclement

codespell_lib/data/dictionary_rare.txt

@@ -16,7 +16,7 @@ bellow->below
 bloc->block
 blocs->blocks
 bodgy->body
-bu->by, be,
+bu->by, be, but, bug, bun, bud, buy, bum,
 buss->bus
 busses->buses
 calculatable->calculable