suggest for autocomplete

suggest.txt

### Mapping

```json
           "suggest": {
              "type" : "completion",
              "analyzer" : "simple",
              "search_analyzer" : "simple",
              "payloads" : true
           },
```

### MetaCPAN::Document::File - adding the data at import time

```perl
has suggest => (
    required => 1,
    is       => 'ro',
    lazy     => 1,
    builder  => '_build_suggest',
   # index    => 'not_analyzed',
);

sub _build_suggest {
    my $self = shift;

    my $doc  = $self->documentation;

    return unless $doc;

    my $weight = 1000 - length($doc);

    return {
        input => [ $doc ],
        payload => { doc_name => $doc },
        weight => $weight
    }

}
```

### Running a query
```sh
curl -X POST 'localhost:9900/cpan/_suggest?pretty' -d '{
    "my-suggest" : {
        "text" : "multiple::modu",
        "completion" : {
            "field" : "suggest"
        }
    }
}'
```