Installation & Upgrade Documentation Changes

[mitchelsellers]

This pull request updates two areas of documentation for installation requirements and upgrade processes to reflect current processes.

Notable changes include.

• Updates to the minimum version requirements to reflect current Microsoft-supported versions. (IE removed SQL Server 2008 which is beyond EOL)
• Simplified version display for the hosting server and IIS versions to match versions that are available
• Updated upgrade documentation to reference the use of the Upgrade Wizard in preparation for support of changes coming in DNN Platform 9.11.0
• Updated upgrade documentation to include a note about the proper roll-back process for failed upgrades.