fix textDocument/reference -> textDocument/references

Author: Strum355

lsif-semanticdb/src/main/java/com/sourcegraph/lsif_semanticdb/LsifWriter.java

@@ -83,7 +83,7 @@ public void emitEdge(String label, int outV, int inV) {
 
   public int emitReferenceResult(int resultSet) {
     int referenceResult = emitObject(lsifVertex("referenceResult"));
-    emitEdge("textDocument/reference", resultSet, referenceResult);
+    emitEdge("textDocument/references", resultSet, referenceResult);
     return referenceResult;
   }