Alter markdown line length recommendation

Author: bencap

.github/instructions/markdown.instructions.md

@@ -29,7 +29,7 @@ Follow these guidelines for formatting and structuring your markdown content:
 - **Links**: Use `[link text](URL)` for links. Ensure that the link text is descriptive and the URL is valid.
 - **Images**: Use `![alt text](image URL)` for images. Include a brief description of the image in the alt text.
 - **Tables**: Use `|` to create tables. Ensure that columns are properly aligned and headers are included.
-- **Line Length**: Break lines at 80 characters to improve readability. Use soft line breaks for long paragraphs.
+- **Line Length**: Break lines at 400 characters to improve readability. Use soft line breaks for long paragraphs.
 - **Whitespace**: Use blank lines to separate sections and improve readability. Avoid excessive whitespace.
 
 ## Validation Requirements