btrfs-progs: Documentation: fix broken conversion

btrfs-progs: Documentation: fix broken conversion

Fixes various formatting issues:

Fixes quoting issues in various manpages. Before/After excerpts for
mkfs.btrfs(8), btrfs-qgroup(8):

    mkfs.btrfs [-A|--alloc-start '<alloc-start>']
    mkfs.btrfs [-A|--alloc-start <alloc-start>]
    id 0/<subvolume id>''
    id 0/<subvolume id>
    If multiple '<attr>'s is given, use comma to separate.
    If multiple <attr>s is given, use comma to separate.

The one that is most apparent is the removal of text in
btrfs-subvolume(8) and others. Before/After:

    list [options] [-G <value>] [-C <value>] [--sort=rootid,gen,ogen,path] <path>
    list [options] [-G [+|-]<value>] [-C [+|-]<value>] [--sort=rootid,gen,ogen,path] <path>
    create [-i <qgroupid>] <name>
    create [-i <qgroupid>] [<dest>]<name>

This happens because `<foo>` was replaced by `'<foo>'` in the sed
expression, which is then treated as a constrained quote. As a result,
the `[...]` before the string gets interpreted as "quoted text
attributes".

In this patch, the sed expression is dropped and asciidoc is configured
to recognize `<...>` as a unconstrained quoted string (such that
`<attr>s` is correctly emphasized) and to avoid adding quotes in
contexts where it is not needed.

A remaining problem is that some texts (the one between brackets) do not
add the emphasis for `<...>`. While this could be solved by replacing
`[` and `]` with `&#91;` and `&#93;` using sed, it introduces formatting
problems in btrfs-zero-log(8) because the context is ignored.

Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Signed-off-by: David Sterba <dsterba@suse.cz>