Add CAP icon on staking page

[kappacappa]

To be consistent with the asset icons displayed on the pool page.

---

Bounty

• This issue has a bounty of $20, paid in crypto.
• Bounties are paid upon full resolution of the issue with high quality code, within a reasonable timeframe.
• Important: To be eligible for the bounty, comment below to request assignment to this issue.

[rebel117]

I'd like to work on this issue. I'll add the CAP icon to the staking page to match the asset icons used on the pool page.