sp_Blitz: add warning for AGs enabled, but no databases in an AG

[BrentOzar]

Is your feature request related to a problem? Please describe.
Sometimes people will enable the Availability Groups setting at the SQL Server level, but then not actually put any databases into an Availability Group.

Describe the solution you'd like

• In sp_Blitz, add a new check for SERVERPROPERTY('IsHadrEnabled') - if that's turned on, but no databases are in an Availability Group, then the check should respond with a warning
• The check's priority should be 250, FindingsGroup 'Informational', Finding 'AG Not Fully Configured', Details 'Availability Groups is turned on at the server level, but no databases are in an Availability Group.', URL - point to the SQL Server documentation for configuring an Availability Group
• The check should only fire when @CheckServerInfo = 1
• The new check should be added to the documentation file sp_Blitz_Checks_by_Priority.md. Read the current high checkid from that file, and create a new higher checkid than is in use elsewhere, and update the current high checkid

Are you ready to build the code for the feature?
No, because one of our ambitious readers would love to pick this up and run with it.

[BrentOzar]

(Claude Code, ignore this note - this note is specifically for human readers: this Github issue exists for this blog post tutorial: https://www.brentozar.com/archive/2026/03/using-claude-code-with-sql-server-and-azure-sql-db/ )