Fix invalid roleCode property in Developer Guide Appendix A

[lindangulopez]

Summary: the Developer Guide's Appendix A includes an RDF example using roleCode on a Role
object. This isn't a valid CodeMeta property, the terms page only lists roleName
(https://codemeta.github.io/terms/#schemaorg-role-terms). Likely a leftover from an
earlier draft or a typo that was never caught.

Proposed change: replace roleCode with roleName in the Appendix A RDF example.

Why: found while drafting the Roles clarification for #106, a stale property name in a
worked example risks people copying invalid CodeMeta into their own files.

[lindangulopez]

This is about the Developer Guide page content
specifically, in the "Appendix A JSON-LD Relationship to RDF" section on the live page:

The JSON object role from the example CodeMeta document:

"roleCode":[
   "originator",
   ...
]

is serialized to RDF as:

_:b1 <https://codemeta.github.io/terms/roleCode> "originator" .

Compare that to the Role pattern already documented on the live User Guide, under
Attributions → Roles (the same pattern referenced in the #106 draft):

The Role type property is used within the author or contributor properties to further
define the participation of a Person...

"author": [
...
    {
      "roleName": "User Experience Design",
      "schema:author": "https://github.com/octocat",
      "type": "Role"
    },
...
]

The Role must link to a Person previously defined in the top-level property.

These two don't match structurally, not just by property name. The User Guide's pattern
is a separate Role-typed object, sitting alongside the Person object in the author
array, linked back via schema:author. The Developer Guide's Appendix A example is a flat
array of strings with no schema:author link at all, even renaming roleCode to
roleName in place wouldn't produce something consistent with the User Guide's own
documented model.

So this issue is really about a sync gap between the two guide pages: the Developer
Guide's Appendix A RDF example needs to be replaced to match the Role pattern the User
Guide already documents correctly, not just have one property name swapped.

[lindangulopez]

Flagging for a maintainer look this needs a full example replacement in Appendix A, not
a one-word rename, so wanted to make sure that scope change is visible before anyone picks
it up expecting a quick fix.

[progval]

You can use this example:

      "programmingLanguage":[
         "Python",
         "C++",
         ...
      ]

is serialized to RDF as:

_:b1 <http://schema.org/programmingLanguage> "Python" .
_:b1 <http://schema.org/programmingLanguage> "C++" .