.NET SDK Missing documentation on Exception MutateInAsync

Lack of documentation on MutateInAsync Exception caused by PathExistsException if the item already exists.

Example Query: 

```

 

await collection.MutateInAsync(key, builder =>

{    builder.ArrayAddUnique(path: "unique_items", value: "foo", createPath: true); }

);

```

The issue https://issues.couchbase.com/browse/NCBC-2831 describes this gap according to the Transaction RFC. However there is no relevant documentation of this Exception in the new Documentation for .net SDK 3.1.*