tag: remove docstring about unexistant feature

This was the intention for first creating the subcommand but since we
still don't have a means of removing old data, this docstring is talking
about a ghost.

I'll remember to push for that use case when we implement data removal.

Signed-off-by: Gabriel Filion <gabster@lelutin.ca>
Reviewed-by: Rob Browning <rlb@defaultvalue.org>
Correct claim about number of packs per backup

The current sentence implies that there is only one pack file per backup
run, which is not necessarily correct.

Because of the "constants" max_pack_size and max_pack_objects that are
used as limits to pack sizes, we may end up with more than one pack per
backup if there is a lot of data that needs to be stored.

Signed-off-by: Gabriel Filion <gabster@lelutin.ca>
[rlb@defaultvalue.org: adjust commit summary]
Reviewed-by: Rob Browning <rlb@defaultvalue.org>
index: Correct inconsitency in documentation of modes

In the optspec, --clear and --check are documented as being modes, but
in the man page they are simple options.

Also, even though --clear and --check are listed as modes in the
optspec, they don't appear in the synopsis line.

According to the code, --clear and --check do behave as modes so we
should be consistent in how we document them.

Signed-off-by: Gabriel Filion <gabster@lelutin.ca>
Reviewed-by: Rob Browning <rlb@defaultvalue.org>
Tested-by: Rob Browning <rlb@defaultvalue.org>
Call add_error() with one arg on readlink failure

...instead of two.

This bug and its solution was found by Ben Kelly.

Signed-off-by: Gabriel Filion <gabster@lelutin.ca>
[rlb@defaultvalue.org: adjust commit message]
Reviewed-by: Rob Browning <rlb@defaultvalue.org>