add lateI value source docString

Author: vigyasharma

lucene/core/src/java/org/apache/lucene/search/LateInteractionFloatValuesSource.java

@@ -25,6 +25,15 @@
 import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.index.VectorSimilarityFunction;
 
+
+/**
+ * A {@link DoubleValuesSource} that scores documents using similarity between a multi-vector query,
+ * and indexed document multi-vectors.
+ *
+ * <p>This is useful re-ranking query results using late interaction models, where documents and queries
+ * are represented as multi-vectors of composing token vectors. Document vectors are indexed
+ * using {@link org.apache.lucene.document.LateInteractionField}.
+ */
 public class LateInteractionFloatValuesSource extends DoubleValuesSource {
 
   private final String fieldName;