feat: change docs build process

[mauromorales]

We've talked about this before, but the current hack we have is starting to get pretty slow, so I wanted us to revisit it again.

Currently, the way we build the website is that we have a script that will loop through all the different branches that have a vX.Y.Z and do a go mod tidy and hugo build. This is not only error prone because at any moment we can delete a branch by mistake but it's also making the process slower every time we add a new release.

Netlify offers the solution to map branches to subdomains, but we tried this with @mudler at some point and we couldn't making it work. Keep in mind that setting this up is not only hard to test because it's DNS but also it's easy to break production. I'd like us to either explore this path again, or come up with a different solution. Ideally a solution that doesn't require to build all the branches every time we release, and every time we push to a PR

[mauromorales]

@mudler could you try asking if we can get a free plan with the CNCF https://contribute.cncf.io/resources/project-services/hosted-tools/ according to CNCF you just need to send them an email via here mentioning we are a sandbox project https://www.netlify.com/contact/