Compile relevant docs on the same page in reference

[olavflar]

After discussion with the rest of the team, we decided to update more on docs.

We have duplicated sites on docs that contain the similar information about a component
Starting with this site
And merging the information on the top of the components on the reference site

To consider; Make sure the headlines make sense, and the right menu make sense, so that the user can scroll and go back to content tha give meaning.

The rest of the components:
Titles and paragraphs
Buttons and links
Input
Date
Checkboxes
Radio button
Dropdown
Help texts
Error messages
File upload