duckdb/Cargo.toml: teach docs.rs about vtab (#445)

Author: ajwerner

crates/duckdb/Cargo.toml

@@ -85,7 +85,7 @@ pretty_assertions = { workspace = true }
 
 
 [package.metadata.docs.rs]
-features = []
+features = ["vtab", "vtab-arrow"]
 all-features = false
 no-default-features = true
 default-target = "x86_64-unknown-linux-gnu"