Add ChangeLog entry for #15351

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

ChangeLog

@@ -16,6 +16,7 @@ phpMyAdmin - ChangeLog
 - issue        Fix double slash in path when $cfg['TempDir'] has a trailing slash
 - issue #14875 Fix shp file import tests where failing when php dbase extension was enabled
 - issue #14299 Fix JS error "PMA_makegrid is not defined" when clicking on a table from the "Insert" tab opened in a new tab
+- issue #15351 Fixed 2FA setting removed each time the user edits another configuration setting
 
 5.0.0 (2019-12-26)
 - issue #13896 Drop support for PHP 5.5, PHP 5.6, PHP 7.0 and HHVM