fix: Update types of .diff API (#617)

pochi-sato · iamkun · commit f0f43d29b52d · 2019-06-18T15:51:45.000+08:00
diff --git a/types/index.d.ts b/types/index.d.ts
@@ -65,7 +65,7 @@ declare namespace dayjs {
 
     format(template?: string): string
 
-    diff(date: ConfigType, unit: QUnitType | OpUnitType, float?: boolean): number
+    diff(date: ConfigType, unit?: QUnitType | OpUnitType, float?: boolean): number
 
     valueOf(): number
 
