install.sh: fix harmless error message on install

This was caused by trying to write to a non existent file, and
changing the order of the cleanup fixed it.

https://forum.rclone.org/t/rclone-v1-65-0-release/43100/18

docs/content/install.sh

@@ -193,12 +193,12 @@ case "$OS" in
     exit 2
 esac
 
-#cleanup
-rm -rf "$tmp_dir"
-
 #update version variable post install
 version=$(rclone --version 2>>errors | head -n 1)
 
+#cleanup
+rm -rf "$tmp_dir"
+
 printf "\n${version} has successfully installed."
 printf '\nNow run "rclone config" for setup. Check https://rclone.org/docs/ for more details.\n\n'
 exit 0