docs: Self review of doc pages

docs/operations/agent-updates.md

@@ -13,8 +13,7 @@ Each server's detail page shows the version it reported at its last sync.
 
 ## Updating from the UI
 
-**Servers → _a server_ → Update agent** pushes `UpdateAgentCmd` with a target
-version. The agent then:
+Open a server and choose **Update agent**. The agent then:
 
 1. Downloads the binary for its platform from the release.
 2. Verifies the SHA-256 against `checksums.txt`.
@@ -35,8 +34,8 @@ irm https://vantage.example.com/update.ps1 | iex
 ```
 
 It does the same download, checksum and replace, then restarts the service. Use
-this when the control plane cannot push for example, when the machine is
-reachable but its command stream is not.
+this when Vantage cannot reach the agent to push the update, but you can still
+reach the machine.
 
 ## Rolling out across a fleet
 
@@ -54,9 +53,8 @@ Do one, confirm it returns to `active`, then do the rest.
 
 ## Version compatibility
 
-The agent API is versioned to tolerate an agent older than the control plane. The
-reverse an agent newer than the control plane is not a case anyone tests.
-Upgrade the control plane first.
+An agent older than your control plane is supported. An agent newer than it is
+not, so upgrade the control plane first.
 
 Agents report their version on every poll, so a fleet running mixed
 versions is visible in the server list rather than something you have to go