Add mispellings->misspellings

As raised by @DimitriPapadopoulos in #2077

codespell_lib/data/dictionary.txt

diff --git a/codespell_lib/data/dictionary.txt b/codespell_lib/data/dictionary.txt
index 6c0e27f..39f933f 100644
--- a/codespell_lib/data/dictionary.txt
+++ b/codespell_lib/data/dictionary.txt
@@ -18951,6 +18951,7 @@
 mispell->misspell
 mispelled->misspelled
 mispelling->misspelling
+mispellings->misspellings
 mispelt->misspelt
 mispronounciation->mispronunciation
 missconfiguration->misconfiguration