conflictGet docs has wrong return type

[yuribro]

The documentation of Index.conflictGet (here for example: https://www.nodegit.org/api/index/#conflictGet) has the wrong return value: it doesn't return a single IndexEntry, but an object with this type:

{
 ancestor_out: IndexEntry | null
 our_out: IndexEntry | null
 their_out: IndexEntry | null
}

See this issue for referenece as well: #1193