doc: shift docs to kathmandu

Context

Following the activation of the Kathmandu protocol, we may say goodbye to the docs of Jakarta, and update all pages accordingly.

Also, the installation scripts in HowToGet have been updated.

Applies to meta-issue #2170

Essentially, performs the same changes as the last shift from Ithaca to Jakarta (!5750 (merged)).

Manually testing the MR

Make the doc, locally and in the CI, and check that there are no errors.

• Contemplate the left menu: there is no more a section for Jakarta.
• All references to protocol pages or labels should go to Kathmandu now (e.g., navigate from shell/cli-commands.rst to the protocol page and back).
• Search for "jakarta" in the left menu's search box: it should only find it in history pages (the changelog, pages under protocols/ and releases/, as an old test network, and in the history of protocol environments).

Verify labels with make -C docs xrefscheck:

• Only a couple of errors should appear on K, concerning refs to the glossary (our script doesn't understand such refs).
• the same for Alpha

Check the installation scripts in the doc:

• locally with make -C docs scriptsindoccheck
• in the CI

NB: Some scripts may fail until the new binary packages for the 014 executables are provided by Serokell.

Checklist

• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR