reorganize networking docs

[sascala]

Description

Urgency

• [ ] Blocker
• [ ] High
• [ ] Medium

Requirements

• Test all commands and procedures.
• Build content locally and test for formatting/links.
• Add redirects to dcos-website/redirect-files.
• Change all affected versions (e.g. 1.7, 1.8, and 1.9).
• See the contribution guidelines.

[sascala]

@pavisandhu Assigning this to you for reference