Create expandable third-level navs for Topology section

[jenny-s51]

These are separated out in the demo-app, so we want to create expandable third level-navs in the topology section for the following:

• [ ] Topology View - all demos in #11 will be listed under this expandable item
• [ ] Topology Pipelines - will include all topology pipelines demos and docs

[jenny-s51]

Closing after discussion with @jeff-phillips-18 - it was agreed that Pipelines will live with the rest of the topology demos