Update README.md

README.md

@@ -82,6 +82,7 @@ If you don't want to cache the cookies, just use the `--no-cookies` option and p
 
 You can configure proxies by setting on your system the environment variable `HTTPS_PROXY` or using the `USE_PROXY` directive into the script.
 
+#### Calibre EPUB conversion
 **Important**: since the script only download HTML pages and create a raw EPUB, many of the CSS and XML/HTML directives are wrong for an E-Reader. To ensure best quality of the output, I suggest you to always convert the `EPUB` obtained by the script to standard-`EPUB` with [Calibre](https://calibre-ebook.com/).
 You can also use the command-line version of Calibre with `ebook-convert`, e.g.:
 ```bash