Remove Binary Installation section from driver documentation

Driver docs (pages https://mongodb.github.io/mongo-csharp-driver/2.10/getting_started/installation/#binary-installation and https://mongodb.github.io/mongo-csharp-driver/2.11/getting_started/installation/#binary-installation) contain section Binary Installation which is not valid, because binaries are not included since 2.10 release (the last release with binary artifacts: https://github.com/mongodb/mongo-csharp-driver/releases/tag/v2.9.2).
The Binary Installation section should be removed.