remove modern f-string syntax, link to docs

my/config.py

@@ -92,6 +92,7 @@ class location:
     class google_takeout_semantic:
         # a value between 0 and 100, 100 being the most confident
         # set to 0 to include all locations
+        # https://locationhistoryformat.com/reference/semantic/#/$defs/placeVisit/properties/locationConfidence
         require_confidence: float = 40
         # default accuracy for semantic locations
         accuracy: float = 100