DOCSP-31630: Typo fix (#4130)

Author: sarah-olson-mongodb

source/reference/method/cursor.allowDiskUse.txt

@@ -95,7 +95,7 @@ following:
      "reading" : {
        "timestamp" : Timestamp(1580247215, 1),
        "value" : 212,
-       "unit" : "Farenheit"
+       "unit" : "Fahrenheit"
      }
    }