Update the postgres version in the document

[stonezdj]

Update the postgres version (15.10) in the document

as mentioned in goharbor/harbor#22120

[gmarav05]

@stonezdj can you assign me this issue?

[Vad1mo]

@stonezdj can you assign me this issue?

We do not assign tasks to people. If you want to work on it then do it and open up a PR!