Make the readme more user friendly

[jacobheun]

Will the many recent updates to libp2p and our Q3 objective to get more people using libp2p directly, it's time to do a full review/audit of the readme. There are issues like #231 that cause confusion and other api inconsistencies that are being addressed; such as #235 and #236. We need to do a full audit of the readme to make sure it's as easy as possible for new users to get started and existing users to upgrade to the latest version.

As libp2p requires many other components to be configured to work optimally, it's important that we showcase those pieces and make it clear how/where they can be used.

[mpetrunic]

Closing as stale, readme has been updated multiple times since this issue has been opened.