Optimize tutorial/example presentation

[salmad3]

Context

• Creates a master doc for tutorial/examples using their current form - based on what we decide for how to present and host examples/tutorials, this can serve as the primary doc as there aren't other tutorials beyond the getting started ones right now in this repo. The master doc is the index file under the "tutorials" directory.
• Based on data over the last few weeks from plausible analytics, the two pages primarily hit are the index pages, and the tutorial primarily used is go-libp2p, so this may improve navigation and also improve visibility for the other implementations.
• Introduces the use of tabs.
• Based on this proposal, this resolves Improve formatting of libp2p getting started #181, add links to particular examples #182, and is part of Improve Examples section #29, Link to examples in Concepts section of docs #168.

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[salmad3]

If this works, this PR will follow an update to the tabs that will add other implementations, following a similar approach to the implementations page, and will address #29

[p-shahi]

LGTM