doc: rev-list-options.adoc: factor out --date alts

We will introduce `--date` to git-format-rev(1) in the next commit and
will need to add it to the documentation. Let’s factor out the option
alternatives so that it can be included in git-format-rev(1).

The initial paragraph of this option mentions things like git-log(1).
We could make it fit in git-format-rev(1) while not changing it for
git-rev-list(1) and related commands with some conditionals like
`ifndef`, but writing a dedicated paragraph is simple enough.

Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/rev-list-option-date-alternatives.adoc

@@ -0,0 +1,55 @@
+--
+`--date=relative` shows dates relative to the current time,
+e.g. ``2 hours ago''. The `-local` option has no effect for
+`--date=relative`.
+
+`--date=local` is an alias for `--date=default-local`.
+
+`--date=iso` (or `--date=iso8601`) shows timestamps in a ISO 8601-like format.
+The differences to the strict ISO 8601 format are:
+
+	- a space instead of the `T` date/time delimiter
+	- a space between time and time zone
+	- no colon between hours and minutes of the time zone
+
+`--date=iso-strict` (or `--date=iso8601-strict`) shows timestamps in strict
+ISO 8601 format.
+
+`--date=rfc` (or `--date=rfc2822`) shows timestamps in RFC 2822
+format, often found in email messages.
+
+`--date=short` shows only the date, but not the time, in `YYYY-MM-DD` format.
+
+`--date=raw` shows the date as seconds since the epoch (1970-01-01
+00:00:00 UTC), followed by a space, and then the timezone as an offset
+from UTC (a `+` or `-` with four digits; the first two are hours, and
+the second two are minutes). I.e., as if the timestamp were formatted
+with `strftime("%s %z")`).
+Note that the `-local` option does not affect the seconds-since-epoch
+value (which is always measured in UTC), but does switch the accompanying
+timezone value.
+
+`--date=human` shows the timezone if the timezone does not match the
+current time-zone, and doesn't print the whole date if that matches
+(ie skip printing year for dates that are "this year", but also skip
+the whole date itself if it's in the last few days and we can just say
+what weekday it was).  For older dates the hour and minute is also
+omitted.
+
+`--date=unix` shows the date as a Unix epoch timestamp (seconds since
+1970).  As with `--raw`, this is always in UTC and therefore `-local`
+has no effect.
+
+`--date=format:<format>` feeds the _<format>_ to your system `strftime`,
+except for `%s`, `%z`, and `%Z`, which are handled internally.
+Use `--date=format:%c` to show the date in your system locale's
+preferred format.  See the `strftime`(3) manual for a complete list of
+format placeholders. When using `-local`, the correct syntax is
+`--date=format-local:<format>`.
+
+`--date=default` is the default format, and is based on ctime(3)
+output.  It shows a single line with three-letter day of the week,
+three-letter month, day-of-month, hour-minute-seconds in "HH:MM:SS"
+format, followed by 4-digit year, plus timezone information, unless
+the local time zone is used, e.g. `Thu Jan 1 00:00:00 1970 +0000`.
+--

Documentation/rev-list-options.adoc

@@ -1132,61 +1132,7 @@ include::pretty-options.adoc[]
 	author's). If `-local` is appended to the format (e.g.,
 	`iso-local`), the user's local time zone is used instead.
 +
---
-`--date=relative` shows dates relative to the current time,
-e.g. ``2 hours ago''. The `-local` option has no effect for
-`--date=relative`.
-
-`--date=local` is an alias for `--date=default-local`.
-
-`--date=iso` (or `--date=iso8601`) shows timestamps in a ISO 8601-like format.
-The differences to the strict ISO 8601 format are:
-
-	- a space instead of the `T` date/time delimiter
-	- a space between time and time zone
-	- no colon between hours and minutes of the time zone
-
-`--date=iso-strict` (or `--date=iso8601-strict`) shows timestamps in strict
-ISO 8601 format.
-
-`--date=rfc` (or `--date=rfc2822`) shows timestamps in RFC 2822
-format, often found in email messages.
-
-`--date=short` shows only the date, but not the time, in `YYYY-MM-DD` format.
-
-`--date=raw` shows the date as seconds since the epoch (1970-01-01
-00:00:00 UTC), followed by a space, and then the timezone as an offset
-from UTC (a `+` or `-` with four digits; the first two are hours, and
-the second two are minutes). I.e., as if the timestamp were formatted
-with `strftime("%s %z")`).
-Note that the `-local` option does not affect the seconds-since-epoch
-value (which is always measured in UTC), but does switch the accompanying
-timezone value.
-
-`--date=human` shows the timezone if the timezone does not match the
-current time-zone, and doesn't print the whole date if that matches
-(ie skip printing year for dates that are "this year", but also skip
-the whole date itself if it's in the last few days and we can just say
-what weekday it was).  For older dates the hour and minute is also
-omitted.
-
-`--date=unix` shows the date as a Unix epoch timestamp (seconds since
-1970).  As with `--raw`, this is always in UTC and therefore `-local`
-has no effect.
-
-`--date=format:<format>` feeds the _<format>_ to your system `strftime`,
-except for `%s`, `%z`, and `%Z`, which are handled internally.
-Use `--date=format:%c` to show the date in your system locale's
-preferred format.  See the `strftime`(3) manual for a complete list of
-format placeholders. When using `-local`, the correct syntax is
-`--date=format-local:<format>`.
-
-`--date=default` is the default format, and is based on ctime(3)
-output.  It shows a single line with three-letter day of the week,
-three-letter month, day-of-month, hour-minute-seconds in "HH:MM:SS"
-format, followed by 4-digit year, plus timezone information, unless
-the local time zone is used, e.g. `Thu Jan 1 00:00:00 1970 +0000`.
---
+include::rev-list-option-date-alternatives.adoc[]
 
 ifdef::git-rev-list[]
 `--header`::