Add flagged day to enum library (#262)

Author: JoshuaDoshua

enum-library.md

@@ -6,6 +6,7 @@ If you wish to contribute an enum, please submit via a pull request.
 
 - [Countries](https://gist.github.com/sirthxalot/24507fb57964d1b7b660f08fdfebf9ce) - submitted by [Alexander Bösch](https://github.com/sirthxalot)
 - [Days of the week](https://gist.github.com/BenSampo/84ffa24efe2b1bc719aba8d1e666b7c3) - submitted by [Ben Sampson](https://github.com/bensampo)
+- [Flagged Days of the Week](https://gist.github.com/JoshuaDoshua/2815e101c0735ac9b833207ffce9ca8e) - submitted by [JoshuaDoshua](https://github.com/joshuadoshua)
 - [Months of the year](https://gist.github.com/BenSampo/46e620affe0e97e489e35e8bce914920) - submitted by [Ben Sampson](https://github.com/bensampo)
 - [Country calling codes](https://gist.github.com/MammutAlex/af182c622fc10991ce42f2397fb54e4a) - submitted by [Alex Kovalchuk](https://github.com/MammutAlex)
 - [RFC 5424 log levels](https://gist.github.com/othyn/fd2fb2e611de832398e42130f2f2143d) - submitted by [Ben Tindall](https://github.com/othyn), [RFC spec](https://tools.ietf.org/html/rfc5424).