Explore use of reflection to populate Summary and Description automatically

[rwxrob]

Now that embed is the conventional way to add documentation to commands, it makes sense to explore ways to put all the documentation for a given command into a single file within the desc directory. In fact, where it is stored does matter, we simply have to use Reflect to look for a string that matches the name of the command.

//go:embed desc/foo.md
var fooCmdDoc string

var fooCmd := &Z.Cmd{
  // ...
}

The performance hit from using Reflect is minimal for this type of operation since it is only to display help and would not affect anything else being called dynamically from the help command itself.

The use of docs should, however, be discouraged since it is used for other things like KEG and GitHub pages sites.