Update docs clarifying description for get_unix_time_from_system on UTC

fix url tag in doc/classes/Time.xml

Co-authored-by: A Thousand Ships <96648715+AThousandShips@users.noreply.github.com>

fix url tag in doc/classes/Time.xml

Co-authored-by: A Thousand Ships <96648715+AThousandShips@users.noreply.github.com>

update get_unix_time_from_system description

Update doc/classes/Time.xml

Co-authored-by: Aaron Franke <arnfranke@yahoo.com>

doc/classes/Time.xml

@@ -7,7 +7,7 @@
 		The Time singleton allows converting time between various formats and also getting time information from the system.
 		This class conforms with as many of the ISO 8601 standards as possible. All dates follow the Proleptic Gregorian calendar. As such, the day before [code]1582-10-15[/code] is [code]1582-10-14[/code], not [code]1582-10-04[/code]. The year before 1 AD (aka 1 BC) is number [code]0[/code], with the year before that (2 BC) being [code]-1[/code], etc.
 		Conversion methods assume "the same timezone", and do not handle timezone conversions or DST automatically. Leap seconds are also not handled, they must be done manually if desired. Suffixes such as "Z" are not handled, you need to strip them away manually.
-		When getting time information from the system, the time can either be in the local timezone or UTC depending on the [code]utc[/code] parameter. However, the [method get_unix_time_from_system] method always returns the time in UTC.
+		When getting time information from the system, the time can either be in the local timezone or UTC depending on the [code]utc[/code] parameter. However, the [method get_unix_time_from_system] method always uses UTC as it returns the seconds passed since the [url=https://en.wikipedia.org/wiki/Unix_time]Unix epoch[/url].
 		[b]Important:[/b] The [code]_from_system[/code] methods use the system clock that the user can manually set. [b]Never use[/b] this method for precise time calculation since its results are subject to automatic adjustments by the user or the operating system. [b]Always use[/b] [method get_ticks_usec] or [method get_ticks_msec] for precise time calculation instead, since they are guaranteed to be monotonic (i.e. never decrease).
 	</description>
 	<tutorials>
@@ -180,7 +180,7 @@
 		<method name="get_unix_time_from_system" qualifiers="const">
 			<return type="float" />
 			<description>
-				Returns the current Unix timestamp in seconds based on the system time in UTC. This method is implemented by the operating system and always returns the time in UTC.
+				Returns the current Unix timestamp in seconds based on the system time in UTC. This method is implemented by the operating system and always returns the time in UTC. The Unix timestamp is the number of seconds passed since 1970-01-01 at 00:00:00, the [url=https://en.wikipedia.org/wiki/Unix_time]Unix epoch[/url].
 				[b]Note:[/b] Unlike other methods that use integer timestamps, this method returns the timestamp as a [float] for sub-second precision.
 			</description>
 		</method>