Onboarding: point "Learn how to get started" link to something more digestable

[humitos]

After the user creates an account, we show the following screen:

The link "Learn how to get started" points to the tutorial, which is a lot of information for a user at this stage. It's also worth to note that the first paragraph of the tutorial says:

In this tutorial you will learn how to host a public documentation project on Read the Docs Community.

which is pretty confusing if the user created an account on Read the Docs for Business.

At Book Club we talk point them to something easier to follow and quicker to start with. Maybe a new "Quickstart with Read the Docs" guide that is tool agnostic and shows all the YAML examples we have in our "Add project" wizard.

[humitos]

Once the page mentioning all the doctools is ready, we can link it to there:

• Add list of supported tools readthedocs.org#11547