bup-prune-older.md: remove fictional --keep option

The documentation lists the "--keep" option, but the actual command
doesn't implement it:

 $ bup prune-older --unsafe --keep 7d,1y,10y,100y
 usage: bup prune-older [options...] [BRANCH...]
 [...]
 error: option --keep not a unique prefix

Signed-off-by: Alexander Barton <alex@barton.de>
[rlb@defaultvalue.org: shorten summary line]
Reviewed-by: Rob Browning <rlb@defaultvalue.org>
Tested-by: Rob Browning <rlb@defaultvalue.org>

diff --git a/Documentation/bup-prune-older.md b/Documentation/bup-prune-older.md
index cbe87c58e8ef47e0510f00bca8f7131cc171abeb..7ba24d7807ffb606421e9ffe8770981de6647ef8 100644 (file)
--- a/Documentation/bup-prune-older.md
+++ b/Documentation/bup-prune-older.md
@@ -62,11 +62,6 @@ calendar, so `--keep-dailies-for 5d` means a period starting exactly
 :   when no smaller time scale --keep option applies, retain the
     oldest save for any year within the given period.
 
---keep ALL,DAILY,MONTHLY,YEARLY
-:   shorthand equivalent to specifying each of the related `--keep-*`
-    options for each period.  If an underscore is specified for a
-    period, then that time-scale will be unaffected by this argument.
-
 --wrt UTC_SECONDS
 :   when computing a keep period, place the most recent end of the
     range at UTC\_SECONDS, and any saves newer than this will be kept.