SLIM-CLI support

[riverma]

Purpose

• Adjustments to SLIM to support slim-cli: https://github.com/nasa-ammos/slim-cli
• No noticeable difference to website other than best practice templates et al now appear as raw text rather than in a nice box like before (this is to support more programmatic downloads rather than just human viewing)

Proposed Changes

• [CHANGE] slim-registry to have a new 'assets' metadata field detailing infusible artifacts like templates, scripts, etc.
• [CHANGE] Best practices guides to support infusible assets by removing Docusaurus styled markdown headings and footers
• [CHANGE] Moved assets for best practice guides to a separate directory under static to support downloadable
• [CHANGE] Improved text in some guides

Issues

• [New Website Feature]: Improved Standards Infusion Process: Self-Service Model and Better Docs #154

Testing

• Tested locally
• Tested extensively with slim-cli (see usage here)

[riverma]

Changes have been viewed by internal team and vetted by users of SLIM-CLI tool. Authorizing a merge.