update calendar demonstration

README.md

@@ -15,6 +15,6 @@ We are Student Cluster Competition Team at Sun Yat-sen University, and conduct r
 
 ## Calendar
 
-<iframe src="https://calendar.google.com/calendar/embed?height=600&wkst=1&bgcolor=%23ffffff&ctz=Asia%2FShanghai&src=c29hcjIwODE1QGdtYWlsLmNvbQ&src=YThqZGQ1bTc1OGdnZTV2ZnFzcGVvMGVpMDhAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ&src=YWRkcmVzc2Jvb2sjY29udGFjdHNAZ3JvdXAudi5jYWxlbmRhci5nb29nbGUuY29t&src=Y2xhc3Nyb29tMTEyMTg4Mjc5MTQyMjQzMDU4Mjk0QGdyb3VwLmNhbGVuZGFyLmdvb2dsZS5jb20&color=%23039BE5&color=%23F4511E&color=%2333B679&color=%23202124" style="border:solid 1px #777" width="800" height="600" frameborder="0" scrolling="no"></iframe>
+<iframe src="https://calendar.google.com/calendar/embed?height=600&wkst=1&bgcolor=%23616161&ctz=Asia%2FShanghai&showTitle=1&showPrint=0&showNav=1&src=YThqZGQ1bTc1OGdnZTV2ZnFzcGVvMGVpMDhAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ&color=%23F4511E" style="border-width:0" width="800" height="600" frameborder="0" scrolling="no"></iframe>
 
-Subscribe: https://calendar.google.com/calendar/ical/a8jdd5m758gge5vfqspeo0ei08%40group.calendar.google.com/public/basic.ics (add this link to your subscription, do NOT download directly).
+Subscribe: [link](https://calendar.google.com/calendar/ical/a8jdd5m758gge5vfqspeo0ei08%40group.calendar.google.com/public/basic.ics) (copy this link and add it to your subscription on iOS or email calendar, do NOT download directly).