feat: display the 'body' of a MR mod on the mod downloader

Signed-off-by: flow <flowlnlnln@gmail.com>

launcher/modplatform/ModIndex.h

@@ -73,6 +73,8 @@ struct ExtraPackData {
     QString sourceUrl;
     QString wikiUrl;
     QString discordUrl;
+
+    QString body;
 };
 
 struct IndexedPack {

launcher/modplatform/modrinth/ModrinthPackIndex.cpp

@@ -87,6 +87,8 @@ void Modrinth::loadExtraPackData(ModPlatform::IndexedPack& pack, QJsonObject& ob
         pack.extraData.donate.append(donate);
     }
 
+    pack.extraData.body = Json::ensureString(obj, "body");
+
     pack.extraDataLoaded = true;
 }