Standardize on RFC 2119 semantics

Author: MariusStorhaug

.github/instructions/universal.instructions.md

@@ -5,9 +5,9 @@ description: Standardize and improve code with consistent formatting, structure,
 
 ## Universal Authoring Guidelines
 
-Lines SHALL not exceed 150 characters.
-Lines SHALL not have trailing whitespace at the end of lines, including blank lines.
-All files MUST end with a single newline.
-Paths SHALL use forward slashes (`/`), not backslashes (`\`) for compatibility across operating systems.
-Files SHALL use UTF-8 encoding.
-Files SHALL use Unix line endings (LF).
+- Lines MUST NOT exceed 150 characters.
+- Lines MUST NOT have trailing whitespace at the end of lines, including blank lines.
+- All files MUST end with a single newline.
+- Paths MUST use forward slashes (`/`), not backslashes (`\`) for compatibility across operating systems.
+- Files MUST use UTF-8 encoding.
+- Files MUST use Unix line endings (LF).