Rename Reference categories Configuration

[e-im]

Initially done at the request of @kennytv as the (Paper) Reference category currently contains just the configuration file.

My plans for the category in the future were:

• Built-in commands overview
• System properties
• possibly other "reference" type stuff I haven't thought of yet

which are also sort of configurations in a sense.

Opened primarily for opinion as it's not something I am so keen on, but at least right now, it does make more sense on the sidebar.

TODO:

There aren't any redirects implemented for the changed URLs. Doing so is a must should this be merged. Unfortunately, GitHub pages does not support proper redirects, so more to be investigated there. ugly solution is just @docusaurus/plugin-client-redirects

[github-actions]

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[Machine-Maker]

I don't really think commands fall under the "Configuration" title.

[e-im]

yeah, as I think about this more and more, especially with the config migration it doesn't really make sense.