Deprecate remark-update-tags

[ptgott]

The remark-update-tags plugin traverses a Markdown AST and replaces tags that use components/syntax from our previous docs site with those available in the new, Docusuarus-based site.

Let's replace these tags permanently in the docs content, then remove remark-update-tags:

• TabItem: use the value attribute #92
• Add a summary to the details component #93
• Replace Notice with Admonition and use supported Admonition types #94
• Unwrap the children of unsupported components #95
• Remove Iconss and VarLists #96
• Remove string styles from nodes #97