[libhandy] doc: Mention NONE removal in migration guide

[Adrien Plazas <aplazas src gnome org>]

commit 472f6ee436e5e2fbde2d7d8600dbc070949fda7e
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Thu Jun 4 18:30:22 2020 +0500

    doc: Mention NONE removal in migration guide
    
    Signed-off-by: Alexander Mikhaylenko <alexm gnome org>

 doc/hdy-migrating-0-0-to-1.xml | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)
---
diff --git a/doc/hdy-migrating-0-0-to-1.xml b/doc/hdy-migrating-0-0-to-1.xml
index 99a54afd..66a22793 100644
--- a/doc/hdy-migrating-0-0-to-1.xml
+++ b/doc/hdy-migrating-0-0-to-1.xml
@@ -141,10 +141,12 @@
     <refsect3>
       <title>Adapt to HdyLeaflet API changes</title>
       <para>
-        The default value for the #HdyLeaflet:transition-type property is
-        changed from “none” to “over”.
+        The “none” transition type has been removed. The default value for the
+        #HdyLeaflet:transition-type property has been changed to “over”.
         “over” is the recommanded transtion for typical #HdyLeaflet use-cases,
-        if this isn't what you want to use, be sure to adapt your code.
+        if this isn't what you want to use, be sure to adapt your code. If
+        transitions are undesired, set #HdyLeaflet:mode-transition-duration and
+        #HdyLeaflet:child-transition-duration properties to 0.
       </para>
     </refsect3>