fix: Update unix-timestamp.md (#134)

* Update unix-timestamp.md

* Update unix-timestamp.md

* Update unix-timestamp.md

* Update unix-timestamp.md

Author: TronNatthakorn

docs/display/unix-timestamp.md

@@ -6,7 +6,7 @@ title: Unix Timestamp
 This returns the Unix timestamp (the number of seconds since the Unix Epoch) of the Day.js object.
 
 ```js
-dayjs('2019-01-25').unix() // 1548381600
+dayjs('2019-01-25').unix() // 1548381600 (Returns Unix timestamp based on local timezone.)
 ```
 
 This value is floored to the nearest second, and does not include a milliseconds component.