Merge pull request arduino#235 from per1234/fix-spellcheck

Fix spell check false positive by ignoring word

Author: per1234

.codespellrc

@@ -1,7 +1,7 @@
 # See: https://github.com/codespell-project/codespell#using-a-config-file
 [codespell]
 # In the event of a false positive, add the problematic word, in all lowercase, to a comma-separated list here:
-ignore-words-list = hel
+ignore-words-list = hel,shiftin
 check-filenames =
 check-hidden =
 skip = ./.git,./test/external