Update Infrastructure documentation to reflect new community-site deployment

[agoose77]

The new deployment process for 2i2c-managed domains that engineers need to follow should resemble something like:

1. Define A (and AAAA) records for the docs.myhub.2i2c.cloud subdomain. These should point to the GitHub pages IP addresses.
2. Create the source repository from a 2i2c-authored template (see [EPIC] Create a skeleton template repository for deploying community documentation #5337)
3. Enable GitHub Pages via GitHub Actions in the source repository
4. Declare the custom domain (docs.myhub.2i2c.cloud) in the GitHub Pages settings
5. Enable HTTPS in the GitHub Pages settings
   We should document this in https://infrastructure.2i2c.org/howto/features/static-sites/#do-a-deploy to reflect the new process for configuring 2i2c infrastructure to serve a site at the given subdomain.
6. Configure the launch buttons to use the adjacent hub compute (see Support the definition of pre-populated Binder and JupyterHub services jupyter-book/myst-theme#512)

We need to formally develop this process and document it in our infrastructure guide.

Definition of Done

• A template site has been deployed to a production cluster
• The process of deploying a site is well documented, and the documentation is accessible for the engineers