Fix astro logo in readme (withastro#2860)

* Fix broken image, make dynamic

* Make part of heading, fix size

* Try and get around markdown parsing

* Make logo smaller

Author: Tc-001

README.md

@@ -1,4 +1,5 @@
-# Astro Docs <img align="right" valign="center" height="52" width="39" src="https://raw.githubusercontent.com/withastro/astro/main/assets/brand/logo.svg" alt="Astro logo" />
+# Astro Docs <picture><source media="(prefers-color-scheme: dark)" srcset="https://astro.build/assets/press/astro-icon-light.png"><source media="(prefers-color-scheme: light)" srcset="https://astro.build/assets/press/astro-icon-dark.png"><img align="right" valign="center" height="79" width="63" src="https://astro.build/assets/press/astro-icon-dark.png" alt="Astro logo" /></picture>
+
 
 To all who come to this happy place: welcome.