[EUI+] Prop tables don't provide enough space for the prop names

[weronikaolejniczak]

The purpose of this task is to fix the prop tables styles so that there's enough space for the prop names.

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Steps to reproduce:

1. Run the new docs locally (go through the steps in the README.md file) or use some staging environment.
2. Go to some component page, e.g. EuiPopover.
3. Scroll down to the prop tables.

Current behavior:

Longer prop names get cut off in the props table.

Expected behavior:

The prop tables column for the prop name adjusts to the content (so that longer prop names can fit).

Important

Consider the edge case of a really long prop name and how it would affect the other columns.