Update README logo (#1514)

README.md

@@ -1,7 +1,12 @@
-<div align="center">
- <img alt="Nebari logo on white background" src="./docs/source/images/nebari_logo.png" width="300" />
-</div>
-<br>
+<p align="center">
+<picture>
+  <source media="(prefers-color-scheme: light)" srcset="https://raw.githubusercontent.com/nebari-dev/nebari-design/main/logo-mark/horizontal/Nebari-Logo-Horizontal-Lockup.svg">
+  <source media="(prefers-color-scheme: dark)" srcset="https://raw.githubusercontent.com/nebari-dev/nebari-design/main/logo-mark/horizontal/Nebari-Logo-Horizontal-Lockup-White-text.svg">
+  <img alt="Nebari logo mark - text will be black in light color mode and white in dark color mode." src="https://raw.githubusercontent.com/nebari-dev/nebari-design/main/logo-mark/horizontal/Nebari-Logo-Horizontal-Lockup-White-text.svg" width="50%"/>
+</picture>
+</p>
+
+---
 
 | Information | Links |
 | :---------- | :-----|