DX-080: Write the pools, earn, referrals, and faucet guides

[IbrahimIjai]

Context

The four remaining product surfaces. Each is small enough that a separate issue
per page would be busywork, and they share a shape: what the page is for, how to
do the main action, and what to check afterwards.

Scope

• /guides/pools: adding and removing liquidity, what a deposit is exposed to
  (link to unified liquidity), and exit conditions.
• /guides/earn: portfolio view, reward accrual, and claiming distributions.
• /guides/referrals: creating and using codes, affiliate tiers, and how
  commissions and discounts are actually calculated.
• /guides/faucet: requesting testnet assets, per-token cooldowns, and what to
  do when a request fails.
• Each page follows the guide template from DX-065 and links to its concepts.

Acceptance criteria

• Every documented action was performed by the author on testnet — confirm
  in the PR.
• Tier and commission numbers come from the code, not from marketing copy.
• Cooldown behaviour matches the faucet implementation.
• All four pages pass check:content, check:links, and prose lint.

Out of scope

• Troubleshooting content (DX-095).

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Spec: docs/dx_1/003_content_map.md §2 · Depends on: DX-079

[Bilalishaq7]

Gooday maintainer,I'd love to take on this task, I can fix this and i'll submit a PR shortly after Assignment