add xfail to known word list

dirk-thomas · rotu · commit 5fbfdfad2714 · 2020-03-27T15:16:31.000-05:00
diff --git a/test/spell_check.words b/test/spell_check.words
@@ -55,3 +55,4 @@ tuples
 unlinking
 veyor
 wildcards
+xfail
