Further improve the local development environment docs

[johnbillion]

Following on from #50058.

There are further improvements that can be made to the project readme file to make it easier for first time contributors to get started.

This ticket will track these changes.

Trac ticket: https://core.trac.wordpress.org/ticket/51414

[johnbillion]

In 49594:

Docs: Correct the Chocolatey package name for Node in the local environment setup instructions.

Props pbearne

See #51414

[johnbillion]

I've been struggling to improve these docs without reimplementing three handbook pages at the same time. This needs a more cohesive approach. I'll raise it with the docs team.

[SergeyBiryukov]

In 49957:

Docs: Clarify the instructions on starting the local environment for the first time.

This adds a mention of cloning the repository before running the npm commands in the terminal.

Props justinahinon.
Fixes #52278. See #51414.

[isabel_brison]

#51591 was marked as a duplicate.

Merged in https://core.trac.wordpress.org/changeset/49594.