added sqlite beta support to C# plugin (#3658)

Author: SockworkOrange

docs/reference/language-support.rst

@@ -20,7 +20,7 @@ New languages can be added via :doc:`plugins <../guides/plugins>`.
 Language  Plugin                            MySQL            PostgreSQL    SQLite
 ========  ===============================  ===============  ============  ===============
 F#        `kaashyapan/sqlc-gen-fsharp`_    Not implemented  Beta          Beta
-C#        `DaredevilOSS/sqlc-gen-csharp`_  Beta             Beta          Not implemented
+C#        `DaredevilOSS/sqlc-gen-csharp`_  Beta             Beta          Beta
 Ruby      `DaredevilOSS/sqlc-gen-ruby`_    Beta             Beta          Beta
 ========  ===============================  ===============  ============  ===============