Update copilot instructions and migrate some skills

.github/copilot-instructions.md

@@ -1,24 +1,20 @@
 # .NET Documentation Guidelines
 
-IMPORTANT: For any Markdown files generated by AI, always disclose that they were created with the assistance of AI. If missing, add the `ai-usage` frontmatter key/value pair:
-
-- When reviewing a PR not created by AI:
+- .NET 8 is an LTS (long-term support) release that's still supported
+- .NET 9 is the latest STS (short-term support) version
+- .NET 10 is the latest LTS version
+- .NET 11 is in preview
 
-  ```markdown
-  ai-usage: ai-assisted
-  ```
-
-- When Copilot generates the article through GitHub without the use of a human:
+IMPORTANT: For any Markdown files generated by AI, always disclose that they were created with the assistance of AI. If missing, add the `ai-usage` frontmatter key/value pair:
 
-  ```markdown
-  ai-usage: ai-generated
-  ```
+| Frontmatter value | When to use |
+|-------------------|-------------|
+| ai-assisted       | When Copilot adds new content to an existing article -or- fixes issues by rewriting content |
+| ai-generated      | When Copilot generates an article with or without a template -or- when Copilot writes all of the content of an article |
 
-- When using an IDE with a human guiding AI:
+Don't apply or change the `ai-usage` value when doing reviews and edits
 
-  ```markdown
-  ai-usage: ai-assisted
-  ```
+Don't apply the `ai-usage` metadata to files in the .github folder.
 
 ## Terminology