Suggestion: Add field to annouce "advertise CSAF"

[tschmidtb51]

We discussed during our TC meeting on 2024-06-26 that we should consider an additional field in the PMD, used to announce whether the issuing party agrees to advertise their CSAF presence in the human-readable web.

A potential implementation could look like:

    "advertise_CSAF_presence": {
      "title": "Advertise CSAF presence", 
      "description": "Decides whether the CSAF presence can be advertised in the human-readable space.",
      "type": "object",
      "required": [
         "category"
      ],
      "properties": {
        "category": {
          "title": "Category of advertisement",
          "description": "Specifies the who may advertise it."
          "type": "string",
          "enum": [
            "none",
            "official",
            "aggregators",
            "press",
            "all"
          ]
        },
        "degree": {
          "title": "Degree of advertisement",
          "description": "Specifies the degree how the advertisement can be fulfilled.",
          "type": "string",
          "enum": [
            "no",
            "sector_industry",
            "name_only",
            "logo"
           ]
         }
      }
    },