Update README.md

Update high level diagram to use POST for refresh requests instead of GET.

Author: kmonsen

README.md

@@ -98,7 +98,7 @@ DBSC(E) removes the vulnerability DBSC has, where a malware, if already present
 
 ## High level overview
 ![High level diagram](reg_and_refresh.svg)
-[Link to editable diagram](https://sequencediagram.org/index.html#initialData=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-IqUmcmqNq+Qj+OeiaahmhabjOraApeQ6ooai6zPuqEu37UGR00tiCCnaw51hJdn6NDdP53Q9Iu9GEEQIGw702r9xPyqT3YaPcUoeFynx-H8EQ0dG-3WC1C5hfgxmfTue4HiisQJEkBBnheuXXkQt4KQ+z4qW+H7XZDcvCnDYXAaB4F6dBsEHghSGPX4aMNZh2GpsWf0k12k35ELU7RmVQxjlKE6eMEx1xORtR3opcxZWy-NOQddXuY1s4+S4LlUX5DUkAENlD0AA)  
+[Link to editable diagram](https://sequencediagram.org/index.html#initialData=A4QwTgLglgxloDsIAIBEAVACgWVckAzshAFCiSzwhJoBCYA9gO4ECmYehyARmeNHEQpUAZXYA3dpyJMScktwC0APiYAuZASgBzBIqgJkAMwA2zEkxXcNAJgAMd5EwD0W3awAm+wzAZJWSAA0yGCsBMB+bMgGMCYArh5hyAAWrCCJYMQMmhD8mqwwcaH5BFp+AHTIyAA6CAASaRkaqKIFimKlUH6KAEqs2lAEEGAg0H4a5ZPIMMkgJiYB2qwAvJPlLbUAFDNzCwhLIawAjnFQoR7GDJnAYFDio6zIANasAJ7INwwMRsjfHwylMJlBAAShICAYEEeDEkmWsPEYLHY0QQUGgDyIbE6fh4Bg8Bm0tW4hE8v0MqXSyJuYQCMFYChUEA0oROYRQMFCD2eb1AZxIECszNYECKhmAcW4Jlg3Ne4Mh0NhPA0HLSUOQACkAOroJzOHbzRb0pTKJksuJszQ6Qxa9D8wWHEVga3ay26UZFI0qdTITAAeREOtcBQ9WOBrlykFDXUMtVqLQA3qg5tpUGo1sFUBBXsBU6gbahgmsAL7x9OoF6vXMAHnFktgAH0K8pUEWWsg5WqYcjvUMro9a1KYDLgmyQHWCMkSsCLPb7I4XL4GE8oI9qBcoziAJIAESJDA87xi8USmN8wGhP0Xy6SmyuOgMyAA1B9RskQbGEBSmmhWgKAMJfNeGggHEEDJPWV4rhsCDcPurzNKgiYbgg9ZQIkSBQEYK4cGmkytqgJDLMsIgMAAto80DkS+gIEGsREdgqyLwnEbCZLEsBPEQUoIE8lzXK+yCuGRBR+FCSAMso8IzAUvGYb8twDAgj6gGBhwnGcSSwXECAXJB9JzCgWk6dMgErsgEIoGaGkeBJ3oAOIAKKBgQwm+P44mWJJtgOLqbliaQrAmFERm6aZjxWecElSakMCyT8EWknpRCsAAHoMpAGWppznCZS5mdSbA0Gu5mQsgqXANZtkaI5zmuaJASkJ58Jzr59XiYFUQJaFeWPKRgxaPs8llSlFWRRZjFwkKrJDMgiRGOwOVMMkUALE4jxLOyYW0ZMVU+v6znBqEyHOKERhHZOtRfuwCFiDA7RAtGiibh4GgANrIcgO4ALotDOXkACx2AAjB+DSUmAN1tB0wKKH+swGvsrAaMhqHodAWHsKskzBPqexLFj6wEeNvyKlJnJqjavnw3jnommoZoWm4zq2gKXkOqKGoukz7qhLtfoBoJbCFEdD1+CdrBnWEF2fo010-rd93YnofThJESPIK9No-UT8ok92Gj3FKHhcp8fx-BENHRn91gtQuYX4MZH07nuB4orECRJAQZ4Xrl15ELeCkPs+Klvh+V0Q-Lwqw2FwGgeBenQbBB4IUhosoWhDWYdhqbFr9xNdpN+TC48H2juOqQeMER1xORtR3opcxZWyu01YLdXuY1s4+S4LlUX5DUkAENlD0AA))  
 The general flow of a secure session is as follows:
 1. The website requests that the browser start a new session, providing an HTTP endpoint to negotiate registration parameters.
 1. The browser creates a device-bound key pair, and calls the registration HTTP endpoint to set up the session and register the public key.