Documentation: Catch up documentation with Framework

[stichbury]

Description

I've recently made some improvements to the framework documentation to add some sphinx extensions with corresponding features. We should have the same on the Viz (and datasets) docs. Please can you factor in some time in the team to do the following:

• Add the video extension for youtube videos (e.g. if you want to include any of Juan Luis' videos). See the Framework PR for details.
• Add a favicon to the Viz docs + add "last updated" to the Viz docs: one PR here
• Update robots.txt to remove older versions from google indexing and also remove latest

[astrojuanlu]

Video extension is taken care of by https://github.com/kedro-org/kedro-sphinx-theme.

Favicon should too, but I don't see it. We should look into it.

Our robots.txt is going to radically change as per kedro-org/kedro#3741.

So the only thing to do on this ticket is to

• Fix favicon directly on kedro-sphinx-theme
• If anything, address Subproject is no longer highlighted kedro-sphinx-theme#4, which we lost when we migrated to the extension. See Create docs project for Kedro-Viz #1586, [Draft, not ready] Update docs front page following design review #1617