Time section: wording clarified, urls updated (#11979)

* Time section: wording clarified, urls updated

There were some uncetrtanties/errors.
Urls updated to point to the latest python docs

* Update source/_docs/configuration/templating.markdown

Co-Authored-By: Franck Nijhof <frenck@frenck.nl>

* wording changed

* note rephrased/moved

Co-authored-by: Franck Nijhof <frenck@frenck.nl>

source/_docs/configuration/templating.markdown

@@ -169,16 +169,20 @@ The same thing can also be expressed as a filter:
 
 ### Time
 
-- `now()` will be rendered as the current time in your time zone.
-  - For specific values: `now().second`, `now().minute`, `now().hour`, `now().day`, `now().month`, `now().year`, `now().weekday()` and `now().isoweekday()`
-- `utcnow()` will be rendered as UTC time.
+- `now()` returns a datetime object that represents the current time in your time zone.
+  - You can also use: `now().second`, `now().minute`, `now().hour`, `now().day`, `now().month`, `now().year`, `now().weekday()` and `now().isoweekday()` and other [`datetime`](https://docs.python.org/3.8/library/datetime.html#datetime.datetime) attributes and functions.
+- `utcnow()` returns a datetime object of the current time in the UTC timezone.
   - For specific values: `utcnow().second`, `utcnow().minute`, `utcnow().hour`, `utcnow().day`, `utcnow().month`, `utcnow().year`, `utcnow().weekday()` and `utcnow().isoweekday()`.
-- `as_timestamp()` will convert datetime object or string to UNIX timestamp. This function also be used as a filter.
-- `strptime(string, format)` will parse a string to a datetime based on a [format](https://docs.python.org/3.6/library/datetime.html#strftime-and-strptime-behavior).
-- `relative_time` will convert datetime object to its human-friendly "age" string. The age can be in second, minute, hour, day, month or year (but only the biggest unit is considered, e.g. if it's 2 days and 3 hours, "2 days" will be returned). Note that it only works for dates _in the past_.
-- Filter `timestamp_local`  will convert an UNIX timestamp to local time/data.
-- Filter `timestamp_utc` will convert a UNIX timestamp to UTC time/data.
-- Filter `timestamp_custom(format_string, local_boolean)` will convert a UNIX timestamp to a custom format, the use of a local timestamp is default. Supports the standard [Python time formatting options](https://docs.python.org/3/library/time.html#time.strftime).
+- `as_timestamp()` converts datetime object or string to UNIX timestamp. This function also be used as a filter.
+- `strptime(string, format)` parses a string based on a [format](https://docs.python.org/3.8/library/datetime.html#strftime-and-strptime-behavior) and returns a datetime object.
+- `relative_time` converts datetime object to its human-friendly "age" string. The age can be in second, minute, hour, day, month or year (but only the biggest unit is considered, e.g. if it's 2 days and 3 hours, "2 days" will be returned). Note that it only works for dates _in the past_.
+- Filter `timestamp_local` converts an UNIX timestamp to its string representation as date/time in your local timezone.
+- Filter `timestamp_utc` converts a UNIX timestamp to its string representation representation as date/time in UTC timezone.
+- Filter `timestamp_custom(format_string, local_time=True)` converts an UNIX timestamp to its string representation based on a custom format, the use of a local timezone is default. Supports the standard [Python time formatting options](https://docs.python.org/3/library/time.html#time.strftime).  
+Note: [UNIX timestamp](https://en.wikipedia.org/wiki/Unix_time) is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970. Therefore, if used as a function's argument, it can be substituted with a numeric value (`int` or `float`):  
+```yaml
+{{ 120 | timestamp_local }}
+```
 
 ### To/From JSON