Tags a doc test as ignored because it relies on an optional feature
@@ -123,7 +123,7 @@ pub trait NamedGraph: Graph {
/// ```
///
/// The implementation backed by RocksDB could be built using `RocksDbDataset::open` and works just like its in-memory equivalent:
-/// ```
+/// ```ignore
/// use rudf::store::RocksDbDataset;
/// let dataset = RocksDbDataset::open("foo.db");
/// ```
