USER_GUIDE.md: Update upper limit of zonedb and zonedbx from 2100 to …

…10000

USER_GUIDE.md

@@ -204,14 +204,14 @@ directories, using 2 different C++ namespaces to avoid cross-contamination:
 * [zonedb/zone_infos.h](src/ace_time/zonedb/zone_infos.h)
  * intended for `BasicZoneProcessor` or `BasicZoneManager`
  * 266 zones and 183 links (as of version 2021a) from the year 2000 until
- 2100, about 70% of the full IANA TZ Database
+ 10000, about 70% of the full IANA TZ Database
  * contains `kZone*` declarations (e.g. `kZoneAmerica_Los_Angeles`)
  * contains `kZoneId*` identifiers (e.g. `kZoneIdAmerica_Los_Angeles`)
  * slightly smaller and slightly faster
 * [zonedbx/zone_infos.h](src/ace_time/zonedbx/zone_infos.h)
  * intended for `ExtendedZoneProcessor` or `ExtendedZoneManager`
  * all 386 zones and 207 links (as of version 2021a) in the IANA TZ Database
- from the year 2000 until 2100.
+ from the year 2000 until 10000
  * contains `kZone*` declarations (e.g. `kZoneAfrica_Casablanca`)
  * contains `kZoneId*` identifiers (e.g. `kZoneIdAfrica_Casablanca`)
 
@@ -3170,7 +3170,7 @@ auto dt = LocalDateTime::forComponents(2000, 1, 1, 0, 0, 61); // invalid second
 
 Another example, the `ZonedDateTime` class uses the generated ZoneInfo Database
 in the `zonedb::` and `zonedbx::` namespaces. These data files are valid from
-2000 until 2100. If you try to create a date outside of this range, an error
+2000 until 10000. If you try to create a date outside of this range, an error
 `ZonedDateTime` object will returned. The following snippet will print "true":
 
 ```C++