docs: basic netlify configuration for book

[salasberryfin]

What type of PR is this?

/kind documentation

What this PR does / why we need it:

This PR adds the basic netlify configuration (plus minimal make tools for building the book) so that we can request a netlify site and a project subdomain.

Together with this PR, I'm opening the necessary requests in the https://github.com/kubernetes/k8s.io/ repository.

Then, when the site is up and running, I'll create a separate PR to add the base structure/contents of the book, so that we can later iterate over this and add new/improve existing topics.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

This the initial PR on an effort to sort the CAPG docs into a book #490.

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

Add Netlify configuration for book

[k8s-ci-robot]

Hi @salasberryfin. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[richardcase]

/ok-to-tesr

[salasberryfin]

@richardcase I think there's a typo in the to-test label and prow didn't start the checks

[cpanato]

/ok-to-test

[salasberryfin]

Fixed tests and it is now ready to be reviewed.

[cpanato]

/approve
/lgtm

thanks for working on this

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cpanato, salasberryfin

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