[REQUEST]: Updates to Reference section

### Description

- [x] Glossary should not be in the middle of the section as seen on [Reference](https://staging-website.elastic.co/docs/reference/): https://github.com/elastic/docs-builder/issues/1045
- [ ] Search should be renamed to Search UI, and first page upleveled. [Search](https://staging-website.elastic.co/docs/reference/search/)
- [ ] Should Rest APIs have a node in the ToC?

### Resources

https://staging-website.elastic.co/docs/reference/

### Which documentation set does this change impact?

Elastic On-Prem and Cloud (all)

### Feature differences

Not feature specific

### What release is this request related to?

N/A

### Collaboration model

The documentation team

### Point of contact.

**Main contact:** @georgewallace

**Stakeholders:**