Update TDS logo with dark mode support (#653)

* Update TDS logo with dark mode support

Author: lesserwhirls

README.md

@@ -1,9 +1,11 @@
-![TDS icon](https://assets.unidata.ucar.edu/images/logos/thredds_tds-150x150.png)
-<br>
-<br>
-
 ## THREDDS Data Server (TDS)
 
+<picture>
+  <source media="(prefers-color-scheme: dark)" srcset="https://assets.unidata.ucar.edu/images/logos/thredds_tds-dm-150x150.png">
+  <source media="(prefers-color-scheme: light)" srcset="https://assets.unidata.ucar.edu/images/logos/thredds_tds-150x150.png">
+  <img width=100 align="left" alt="TDS Logo" src="https://assets.unidata.ucar.edu/images/logos/thredds_tds-150x150.png">
+</picture>
+
 The THREDDS Data Server (TDS) provides metadata and data access to scientific
 datasets. Datasets can be served through OPeNDAP, OGC's WMS and WCS, HTTP, and other
 remote data access protocols. It can be configured to aggregate a collection of