Update DateTime comment for clarity

The comment explaining the function DateTime in temperature.go was modified. The original comment was inaccurate, suggesting it returned boolean when in fact it returns the exact time the temperature data was obtained. The comment was updated to accurately reflect what the function does.

temperature.go

@@ -20,8 +20,8 @@ func (t Temperature) IsAvailable() bool {
 	return !t.na
 }
 
-// DateTime returns true if an Temperature value was
-// available at time of query
+// DateTime returns the time at which the temperature data was
+// generated or fetched
 func (t Temperature) DateTime() time.Time {
 	return t.dt
 }