Makes update_api_doc case insensitive

bin/update_api_doc.sh

@@ -7,5 +7,5 @@ if test -z "$next"; then
   echo "\$ ./bin/update_api_doc.sh <NEXT>"
   echo "See the Release Management Documentation for an example."
 else
-  find src -name '*.ml*' -exec sed -i -e "s/Frama-C+dev/${next}/g" '{}' ';'
+  find src -name '*.ml*' -exec sed -i -e "s/Frama-C+dev/${next}/gI" '{}' ';'
 fi