* Update tiktok.svg
This file is bigger by 38 bytes (446 => 484) but it avoids the use of `<!ENTITY ...>` and `<!DOCTYPE ...>` and as consequence:
- It respect the template starting with `<svg xmlns="http://www.w3.org/2000/svg" ...>`.
- This `svg` code can be integrated directly in `html`.
* Update README.md
Update the size of `tiktok.svg`.