Added add_span() method to MultiTermToken

Change-Id: Iabe067079c47ac49995cfc66d18f7d78768bc25e
diff --git a/Changes b/Changes
index a28b5e6..2e14f56 100644
--- a/Changes
+++ b/Changes
@@ -9,6 +9,7 @@
         - Remove MultiTerm->add() in favor of
           MultiTerm->add_by_term().
         - Optimization by reducing calls to _offset().
+        - Introduced add_span() method to MultiTermToken.
 
 0.40 2020-03-03
         - Fixed XIP parser.