feat: add XRPL node setup guide

[k4m4]

Add instructions for setting up Ripple's XRPL rippled Testnet & Mainnet validator node.

These instructions are just about setting up the XRPL node. Regarding updating ampd to communicate with this node, I'd recommend adding something along these lines in the relevant location:

## Update `ampd` configuration

Assuming you [have set up your Axelar Amplifier `ampd` verifier node](https://docs.axelar.dev/validator/amplifier/verifier-onboarding/),
append the following handlers to the end of your configuration file (usually `~/.ampd/config.toml`):

[[handlers]]
multisig_contract="axelar19jxy26z0qnnspa45y5nru0l5rmy9d637z5km2ndjxthfxf 5qaswst9290r"
multisig_prover_contract="axelar1ys83sedjffmqh70aksejmx3fy3q2d7twm3msurk 7wn3l6nkwxp0sfelzhl"
type="XRPLMultisigSigner"

[[handlers]]
chain_name="xrpl"
chain_rpc_url="http://localhost:5005"
cosmwasm_contract="axelar1w0cwqtytmjuhak4v0rd4fy65pugqcxz4g48n6puw55zcy8 96e6ksn9gkj2"
type="XRPLMsgVerifier"

If you are running `rippled` in a different server, ensure that their communication is secured via HTTPS and/or VPN,
and replace the `XRPLMsgVerifier`'s `chain_rpc_url` with the URL to your `rippled` node.

Finally, restart `ampd` so these changes take effect.

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Name	Status	Preview	Comments	Updated (UTC)
axelar-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Feb 19, 2025 2:09pm

[Olanetsoft]

@k4m4, it seems your base branch is outdated, blocking this PR from being merged. Kindly take a look. Thank you.

[talalashraf]

Missing navigation file change e.g this PR