Update pg package URL in deployment instructions

[pinarpink]

Describe the bug (current behaviour)

The following command in deployment.md no longer works as packages have moved

sudo yum install https://download.postgresql.org/pub/repos/yum/10/redhat/rhel-7-x86_64/pgdg-centos10-10-2.noarch.rpm

Expected behavior

In deployment instructions, provide link to postgres package url builder to allow deployer to find correct url.

Environment:

• Deployment: https://10.240.16.89/
• Version [e.g. 1.2.0]
• Browser [e.g. Firefox 68.x]

Additional information (error logs, screenshots)

[vildead]

fixed by #182