Debian Support

The installation instructions have a 3rd step of associating an artifact with content. They claim:

```
http POST $BASE_ADDR/pulp/api/v3/content/deb/packages/ _artifact=http://localhost:24817/pulp/api/v3/artifacts/1/ filename=my_content
```

Except that using this gives:

```{
"_relative_path": [
"This field is required."
],
"architecture": [
"This field is required."
],
"description": [
"This field is required."
],
"maintainer": [
"This field is required."
],
"package_name": [
"This field is required."
],
"sha256": [
"This field is required."
],
"version": [
"This field is required."
]
}
```

It turns out one must manually add a ton of information. It seems odd to have to add that information since most of it should be known by pulp from the artifact. If it must be provided the instructions should be expanded to add that.

Further, it's unclear what `_relative_path` needs to be.