Runbook: also add the new collection to navigation.yml (top nav)

The cutover nav steps covered _data/nav/<key>.yml and _data/nav_map.yml but not
_data/navigation.yml (the top product bar). Without adding the new collection
there, the product's top-nav link isn't marked active on the new version's pages
(e.g. /openvox/9.x/). Add a step to update the product's collections list.

Part of #325.

Signed-off-by: Michael Harp <mike@mikeharp.com>

Author: miharp

MAINTAINING.md

@@ -104,6 +104,16 @@ is **not yet** the stable release. `latest` stays on the current major.
      base: /openvox/9.x/
    ```
 
+   Finally, add the new collection to OpenVox's entry in `_data/navigation.yml` (the
+   top product bar) so the "OpenVox" link is marked active on the new version's pages
+   too:
+
+   ```yaml
+   - title: OpenVox
+     url: /openvox/latest/
+     collections: [openvox_latest, openvox_9x, openvox_8x]   # add openvox_9x
+   ```
+
 5. **Add the version to `_data/products.yml`** (newest first), keeping `latest: 8x`
    for now: