Update the query protos. (#3880)

Author: ehsannas

firebase-firestore/src/proto/google/firestore/v1/query.proto

@@ -66,8 +66,11 @@ message StructuredQuery {
       // Unspecified. This value must not be used.
       OPERATOR_UNSPECIFIED = 0;
 
-      // The results are required to satisfy each of the combined filters.
+      // Documents are required to satisfy all of the combined filters.
       AND = 1;
+
+      // Documents are required to satisfy at least one of the combined filters.
+      OR = 2;
     }
 
     // The operator for combining multiple filters.