Update xlf copilot instructions (#49780)

Author: jjonescz

.github/copilot-instructions.md

@@ -11,8 +11,8 @@ Output Considerations:
 - When considering how output should look, solicit advice from baronfel.
 
 Localization:
-- Avoid modifying .xlf files and instead prompt the user to update them using the `/t:UpdateXlf` target on MSBuild.
+- Avoid modifying .xlf files and instead prompt the user to update them using the `/t:UpdateXlf` target on MSBuild. Correctly automatically modified .xlf files have elements with state `needs-review-translation` or `new`.
 - Consider localizing strings in .resx files when possible.
 
 Documentation:
-- Do not manually edit files under documentation/manpages/sdk as these are generated based on documentation and should not be manually modified.
+- Do not manually edit files under documentation/manpages/sdk as these are generated based on documentation and should not be manually modified.