Update ⚡️Onboarding - Restore a wallet for Lightning

[danielnordh]

As outlined in #519, updates this page for Lightning.
Also includes some shortening and readability updates.

Preview: https://deploy-preview-524--sad-borg-390916.netlify.app/guide/onboarding/restoring-a-wallet/

[GBKS]

Also looks good. A few thoughts:

• Should we note that this backup does not include user data (contacts, transaction notes, etc)
• Are there any other UX recommendations we can add? Any tips for copy, letting users ensure everything is there post import, etc.
• Can you think of ways we can improve the visuals on this page? We could show an example screen for each of the options.

[danielnordh]

• Should we note that this backup does not include user data (contacts, transaction notes, etc)
• Are there any other UX recommendations we can add? Any tips for copy, letting users ensure everything is there post import, etc.

Added note about what's not restored 31f2cc8, and recommendation bubble c03962c

[pavlenex]

LGTM, the only thing that bothers me is:

This is particularly true for a wallet holding bitcoin on the Lightning network, and restoring should be done with the application originally used.

I think we should recommend that wallets should strive for vendor independency and interoperability.

Where:

Vendor independency: Can you restore the client w/o the vendor (backup data doesn't reside on vendor servers)?
Interoperability: the ability to restore in a different environment.

But I personally am not familiar with best practice neither I'm sure the protocol matured for this problem in particular.

[danielnordh]

Think this is good to merge now.
Any following changes can be a new PR.

[pavlenex]

LGTM. My earlier comment about backups aren't really blocker since Daniel has asked in LDK slack and it seems unique backup methods are unlikely to happen between implementations.