Drop Windows-ZVM recipe; ZVMA is now the canonical Zerto example

The Windows ZVM is largely deprecated in favor of the ZVMA on
Kubernetes, so the older recipe and its companion sender script are
gone. The ZVMA recipe is promoted to canonical and its header no
longer references the deleted recipe.

- delete docs/recipes/zerto-pre-post-scripts.md (Windows-ZVM-only)
- delete scripts/examples/zerto-post-failover.ps1 (curl.exe sender)
- promote ZVMA recipe in README, docs/README, installation, sync-wiki

If anyone still needs the DNS-update / service-check handler from
the deleted recipe it's available in git history (commit before this
one). Happy to re-resurrect into a generic post-failover recipe if
folks ask.

docs/installation.md

@@ -76,7 +76,7 @@ The endpoint appears in the grid. Right-click it → **Copy URL**, paste into a
 { "runId": "...", "exitCode": 0, "durationMs": 134, "stdout": "pong\r\n", ... }
 ```
 
-That's it. Real-world recipes start with [Zerto pre/post scripts → AD / DNS update](recipes/zerto-pre-post-scripts.md).
+That's it. Real-world recipes start with [Zerto ZVMA pre/post → notify + VM health check](recipes/zerto-zvma-pre-post.md).
 
 ## Silent / unattended install