Fix link - Update README.md (#449)

* Fix link - Update README.md

[skip ci]

* Revert "time-zone" rename

---------

Co-authored-by: Curtis Vogt <curtis.vogt@gmail.com>

README.md

@@ -15,7 +15,7 @@ TimeZones.jl
 
 * A new time zone aware TimeType: ZonedDateTime
 * Support for all time zones in the IANA time zone database (also known as the tz/zoneinfo/Olson database)
-* ZonedDateTime-Period arithmetic [similar to that of DateTime](https://docs.julialang.org/en/stable/manual/dates/#TimeType-Period-Arithmetic-1)
+* ZonedDateTime-Period arithmetic [similar to that of DateTime](https://docs.julialang.org/en/v1/stdlib/Dates/#TimeType-Period-Arithmetic)
 * Local system time zone information as a TimeZone
 * Current system time in any TimeZone
 * Support for reading the [tzfile](https://man7.org/linux/man-pages/man5/tzfile.5.html) format