docs: mention theseus in the readme and docs landing page diagram

Author: cpcloud

README.md

@@ -154,6 +154,7 @@ Ibis supports nearly 20 backends:
 - [SQL Server](https://ibis-project.org/backends/mssql/)
 - [SQLite](https://ibis-project.org/backends/sqlite/)
 - [Snowflake](https://ibis-project.org/backends/snowflake)
+- [Theseus](https://voltrondata.com/start)
 - [Trino](https://ibis-project.org/backends/trino/)
 
 ## How it works

docs/backends_sankey.py

@@ -40,6 +40,7 @@ def to_greyish(hex_code, grey_value=128):
         "RisingWave",
         "Snowflake",
         "SQLite",
+        "Theseus",
         "Trino",
     ],
     list(category_colors.keys())[2]: ["Polars"],