chore(webapi): Remove specific mediatypes on ContentValueDto (#1614)

<!--- Provide a general summary of your changes in the Title above -->

## Description

<!--- Describe your changes in detail -->

## Related Issue(s)

- #1613

## Verification

- [ ] **Your** code builds clean without any errors or warnings
- [ ] Manual testing done (required)
- [ ] Relevant automated test added (if you find this hard, leave it and
we'll help out)

## Documentation

- [ ] Documentation is updated (either in `docs`-directory, Altinnpedia
or a separate linked PR in
[altinn-studio-docs.](https://github.com/Altinn/altinn-studio-docs), if
applicable)

docs/schema/V1/swagger.verified.json

@@ -315,7 +315,7 @@
         "additionalProperties": false,
         "properties": {
           "mediaType": {
-            "description": "Media type of the content (plaintext, Markdown). Can also indicate that the content is embeddable.",
+            "description": "Media type of the content, this can also indicate that the content is embeddable.\nFor a list of supported media types, see (link TBD).",
             "type": "string"
           },
           "value": {
@@ -6970,4 +6970,4 @@
       "url": "https://altinn-dev-api.azure-api.net/dialogporten"
     }
   ]
-}
+}

src/Digdir.Domain.Dialogporten.Application/Features/V1/Common/Content/ContentValueDto.cs

@@ -11,7 +11,8 @@ public sealed class ContentValueDto
     public List<LocalizationDto> Value { get; set; } = [];
 
     /// <summary>
-    /// Media type of the content (plaintext, Markdown). Can also indicate that the content is embeddable.
+    /// Media type of the content, this can also indicate that the content is embeddable.
+    /// For a list of supported media types, see (link TBD).
     /// </summary>
     public string MediaType { get; set; } = MediaTypes.PlainText;
 }