use app.json instead of process.json

[gabx]

• process.json does not exist and when reading the wiki, app.json is indeed the correct file
• fill the app.json.example, otherwise it is exactly the same file as app.json. So either fill it or delete it
• remove any path mention of ~. There is no reason to invoke the user home directory, neither state that eth-net-intelligence-api folder is the home.