Document new features for 2021.06

[kprosise]

Some, though not all, new features and supported solutions have been documented. Absent is SDE upgrade info, TN48m and DENT, which will be done in a separate commit after those items have been added to the wiki.

Page rendering and links were checked locally and no issues were found that relate to changes made in this commit.

This commit applies to mion-docs#219

Signed-off-by: Katrina Prosise igorina@toganlabs.com

Build and test

• [x] Build command: mkdocs serve
• [x] Smoke tested on: N/A
• [x] all other steps taken to validate the pull request

Checklist

• [x] All relevant issues have been updated
• [x] Reviewers have been added and a maintainer has been assigned
• [x] A Label, Project and Milestone have all been added
• [x] The relevant documentation/wiki/README have been updated and complies with the NGL Style and Communication Guide
• [x] Git commits comply with the NGL Git Workflow and have DCO signoff
• [x] Yocto code complies with the OpenEmbedded Style Guide