Add iff -> if

codespell_lib/data/dictionary.txt

diff --git a/codespell_lib/data/dictionary.txt b/codespell_lib/data/dictionary.txt
index 7217fa7..09eb7ba 100644
--- a/codespell_lib/data/dictionary.txt
+++ b/codespell_lib/data/dictionary.txt
@@ -2148,6 +2148,7 @@
 ideosyncratic->idiosyncratic
 idesa->ideas, ides,
 idiosyncracy->idiosyncrasy
+iff->if
 Ihaca->Ithaca
 illegimacy->illegitimacy
 illegitmate->illegitimate