Create docs for new wasp-cli

[Dr-Electron]

Describe the solution you'd like

To prepare for the release of the new wasp-cli we should update the docs.
Changes needed:

• We now have wallet providers.
  • How do i migrate from the plain text seed?
  • How do I switch wallet provider
• Config file is now stored in ~/.wasp-cli/wasp-cli.json by default. -c can be used to override the default