simpler docstring for _scalar_sign

Author: jpbrodrick89

lineax/_operator.py

@@ -1987,7 +1987,7 @@ def _(operator, check=check):
 
 
 def _scalar_sign(scalar) -> int | None:
-    """Returns 1 if positive, -1 if negative, 0 if zero, None if unknown (traced)."""
+    """Returns scalar sign if known at trace time otherwise None."""
     try:
         if scalar > 0:
             return 1