Update the doc that refers to the removed column of pg_replication_slots.

[Zhijie Hou (Fujitsu)]

Hi,

I noticed one minor thing that the upgrade doc refers to the old 'conflicting'
column of pg_replication_slot. As the column has been changed to 
'conflict_reason', 
I think the doc needs to be updated like the attachment.

Best Regards,
Hou Zhijie

0001-Update-the-doc-for-upgrading-slots.patch
Description: 0001-Update-the-doc-for-upgrading-slots.patch