add script to call codespell utility

scripts/codespell.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+codespell \
+  --skip './.git,./Pods,./deltachat-ios/Assets,Localizable.strings,Localizable.stringsdict,InfoPlist.strings,./deltachat-ios/libraries/deltachat-core-rust' \
+  --ignore-words-list curveLinear