Use discard variable for unused variable and use raw literal string f…

…or the readme

src/Nexus/Extensions/Sources/Sample.cs

@@ -153,7 +153,7 @@ public async Task ReadAsync(
             {
                 cancellationToken.ThrowIfCancellationRequested();
 
-                var (catalog, resource, representation, parameters) = catalogItem;
+                var (catalog, resource, representation, _) = catalogItem;
 
                 // check credentials
                 if (catalog.Id == RemoteCatalogId)
@@ -253,19 +253,20 @@ internal static ResourceCatalog LoadCatalog(
 
         if (catalogId == RemoteCatalogId)
             catalogBuilder.WithReadme(
-@"This catalog demonstrates how to access data sources that require additional credentials. These can be appended in the user settings menu (on the top right). In case of this example catalog, the JSON string to be added would look like the following:
+"""
+This catalog demonstrates how to access data sources that require additional credentials. These can be appended in the user settings menu (on the top right). In case of this example catalog, the JSON string to be added would look like the following:
 
 ```json
 {
-    ""Nexus.Sources.Sample"": {
-        ""user"": ""test"",
-        ""password"": ""1234""
+    "Nexus.Sources.Sample": {
+        "user": "test",
+        "password": "1234"
     }
 }
 ```
 
 As soon as these credentials have been added, you should be granted full access to the data.
-");
+""");
 
         return catalogBuilder.Build();
     }