Feature/rework navigation

[SirDany]

• Updates navigation in menu
• Adds overview page for documentation
• Retrieves remote documentation, adds pages & links to them
• Use gatsby-image instead of raw css
  -> Loading images from low to high res instead of popping up when loaded
  -> Reworked intro component to hold the image instead as background (image will be behind everything inside the intro)

[J12934]

Ehm any idea what is going on here?

Also Build Warnings:

warn ESLintError:
/Users/jannikhollenbach/src/securecodebox.github.io/src/pages/getStarted/index.js
  30:17  warning  Emojis should be wrapped in <span>, have role="img", and have an accessible description
with aria-label or aria-labelledby  jsx-a11y/accessible-emoji

✖ 1 problem (0 errors, 1 warning)
warn ESLintError:
/Users/jannikhollenbach/src/securecodebox.github.io/src/templates/doc.js
  4:8  warning  'Sidebar' is defined but never used  no-unused-vars

✖ 1 problem (0 errors, 1 warning)

[SirDany]

The filter is intentional, since the bullet points are all nonsense and the whole design is still object of discussion I only wanted to represent the area where something could be, e.g. some quicklinks or contents of the documentation. If it is irritating I can remove this effect.
Emojis is pretty obvious fixable, and the sidebar was a preperation for the layout, but can be removed, since it is not used atm.