[backlog] Add user bio & links support

[o-az]

Backlog

more personable experience. Links and bio empty by default, up to address owner to fill them out. Use ens bio data by default

e.g.,

{
  "address": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
  "ens": "vitalik.eth",
  "bio": "anything user wants to put, with character limit, empty by default",
  "links": [
    {
      "name": "github",
      "url": "https://github.com/vbuterin"
    },
    // ...
  ]
}