Add ChangeLog entry for #15876 and 551929a

Signed-off-by: William Desportes <williamdes@wdes.fr>

ChangeLog

@@ -50,6 +50,8 @@ phpMyAdmin - ChangeLog
 - issue #15970 Removed wrong html a tag on "Replication status" header
 - issue        Add missing css classes on some buttons
 - issue #15937 Make modals draggability/expand (down) work after a screen zoom change
+- issue        Fix php notice "Undefined index: on_delete" while creating a foreign key
+- issue #15876 Fixed select "IN (...)" is a simple select instead of a multiple select
 
 5.0.1 (2020-01-07)
 - issue #15719 Fixed error 500 when browsing a table when $cfg['LimitChars'] used a string and not an int value