docs add demos

scripts/genexamplelist.sh

@@ -3,7 +3,7 @@ echo "/* Autogenerated */"
 echo '#include <stddef.h>'
 echo '#include "examplelist.h"'
 TMPFILE=$(mktemp)
-find examples -name \*.h | xargs grep -h "^void lv_example" | sed 's/(/ /g' | awk '{print $2}' > $TMPFILE
+find examples demos -name \*.h | xargs grep -hE "^void lv_(example|demo)" | sed 's/(/ /g' | awk '{print $2}' > $TMPFILE
 cat $TMPFILE | while read -r line; do
 echo "extern void ${line}(void);"
 done