feat: add links to every pg version changes descriptions

Description

In cases when we have different versions on several servers we see in recommendations only one link to why-upgrade.depesz.com.

In this MR I have added links for every version.

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes and they have been reviewed OR there are no API changes

Related issue

Examples

[P2] The minor versions being used (`9.6.12`, `9.6.11`) are not up-to-date (the newest version: `9.6.13`). See the full list of changes [between 9.6.12 and 9.6.13](https://why-upgrade.depesz.com/show?from=9.6.12&to=9.6.13) and [between 9.6.11 and 9.6.13](https://why-upgrade.depesz.com/show?from=9.6.11&to=9.6.13).

Closes #456 (closed)