Remove refund copy from public docs

Keysat has no refund functionality — refunds are handled out-of-band in the
payment processor (the v0.3 revoke-on-refund webhook hook is currently a
no-op). Drop refund mentions so the docs do not describe a flow the daemon
does not implement.

agent.html

@@ -168,7 +168,7 @@ curl https://your-keysat-host/v1/admin/licenses?status=active \
     <pre><code>curl -X POST $KS/v1/admin/licenses/$LICENSE_ID/revoke \
   -H "Authorization: Bearer ks_..." \
   -H "Content-Type: application/json" \
-  -d '{"reason":"refund issued"}'</code></pre>
+  -d '{"reason":"customer request"}'</code></pre>
     <p>Idempotent. The next online validate from the buyer's app returns <code>reason: revoked</code>.</p>
     <p><em>Scope required: <code>licenses:write</code>.</em></p>