Package description field "Related" for related packages

I think it is good style for a package to mention alternative implementations or otherwise related packages. Currently I write this information in the Description field, but a specialised field could be parsed by the Hackage server and be displayed with hyperlinks to the related packages.
The simplest implementation would be just a list of package names like

```
Related: containers, array
```

However, an additional text explaining the relation to the current package would be nice, too. Maybe the syntax of the Source-Repository field can be copied.