Create single content section in Elements website

[amyhupe]

What

Create a "content" section that can house multiple single-page guides, to replace the brand-specific content sections that exist today e.g. https://elements.springernature.com/nature/content

Why

Our content guidance is not brand specific - it generally applies to all brands, so this helps us reduce duplication.

We also need to update our content guidance, so this gives us a good excuse to do that.

Done when

• [x] Content sections have been removed from the brand sections (Perhaps keeping the Nature content somewhere in an archive if possible, so we can refer to it if we need it)
• [x] Elements.springernature.com/content section has been created, with a landing / introduction page
• [x] A-Z styleguide has been added
• [x] Content section is linked to from the main navigation
• [x] Styleguide is published
• [x] Content review by Alex

Anything else?

The first piece of content published will be the new A-Z styleguide which has been worked on by Gaynor Burns.

[sturobson]

Perhaps keeping the Nature content somewhere in an archive if possible, so we can refer to it if we need it

I'm not currently planning on removing the /content/ folder for brands so nature's content can still be found here. Is that ok?

[amyhupe]

@amyhupe to send draft A-Z styleguide and introduction page content so @sturobson can generate previews to check with Gaynor

[sturobson]

[sturobson]