Documentation changes

I'm not really sure where to lodge this, as this was originally about the node.js connector documentation, but it really is something that affects all of MariaDB's documentation. Having the connector documentation in this repo was nice because it allowed one to easily tell what changed between connector versions, which is especially important for checking when things like default values change. Since the documentation is now outside of the repo and the project now links to the website for docs (even though there is [a `mariadb-docs` repo](https://github.com/mariadb-corporation/mariadb-docs/tree/main/connectors/mariadb-connector-nodejs)), there is no way to view the documentation for specific versions, do diffs between versions, or otherwise find out the history of features/behaviors/etc. As I mentioned, this is really a general documentation issue as I've additionally run into this before also with the MariaDB server documentation where some feature or SQL function is documented but then come to find out through unnecessary additional research or trial and error that it's only available in some newer version that I'm not using/can't use. Thankfully not all of the MariaDB documentation is this bad. For example, while not perfect, the server options/variables documentation more often than not will include some helpful version information (e.g. "introduced: x.y.z", "deprecated: x.y.z", or "removed: x.y.z"). I don't have super strong opinions on the best way to provide this information, but I would say that perhaps starting out following the way node.js handles this in their documentation (by providing a collapsible history section per feature/section) would go a long way to educating people about changes to the various parts of the MariaDB ecosystem.