Merge in wiki docs

[rvl]

• Moves the documentation from the cardano-wallet Wiki in the main repo so that it's closer to the code.
• Process docs move into https://github.com/input-output-hk/adrestia.
• Brings in the user-guide docs which used to be in https://github.com/input-output-hk/adrestia/wiki.
• Re-organise merged docs a little.
• Add emanote build.

Issue Number

ADP-1254