Sticky scroll navigation

[Morgy93]

The navigation on the left side should be sticky while scrolling so that you have access to it all the time.

Example: https://docusaurus.io/docs/styling-layout (just scroll down if the page is wide enough to show the left side navigation)

Currently you lose focus quickly if you scroll down on pages like https://devdocs.mage-os.org/docs/main/overview-of-magento-2-development#models

[DavidLambauer]

The navigation grows enormously when you open specific trees. Having it sticky would mean different scrollable divs, which I dislike. You can press pageup/pagedown on your keyboard.

[DavidLambauer]

To be clear. I love the idea of having a site where you can focus on the content in its purest form. No distractions, nothing to click on. Just read the docs, nothing else...