docs: add Related sections to install and help pages

- install/docker.md: link to podman, clawdock, updating, config
- install/node.md: link to overview, updating, getting-started
- install/updating.md: link to overview, doctor, migrating
- help/troubleshooting.md: link to FAQ, gateway/channel/automation troubleshooting, doctor

docs/install/node.md

@@ -136,3 +136,9 @@ export PATH="$HOME/.npm-global/bin:$PATH"
 ```
 
 Add the `export PATH=...` line to your `~/.bashrc` or `~/.zshrc` to make it permanent.
+
+## Related
+
+- [Install Overview](/install) — all installation methods
+- [Updating](/install/updating) — keeping OpenClaw up to date
+- [Getting Started](/start/getting-started) — first steps after install