[EUI+] Update the docs to use side-by-side Guideline convention

[weronikaolejniczak]

The purpose of this task is to update all docs that don't use the side-by-side Guideline convention.

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Run the new docs locally (go through the steps in the README.md file).

Pages:

• Form Layouts > Guidelines page,
• Tabs > Guidelines page (discuss with

Double-check if there are any more pages.

Tip

Use EuiFlexGroup and EuiFlexItem. Leverage gutterSize="m" to create consistent spacing between the guideline items. Use the <Guideline> component (no need to import it) (example).