Examples:
  iwe tree                     Show full tree with markdown links
  iwe tree -f keys             Show tree with document keys only
  iwe tree -f json             Show tree as JSON
  iwe tree -k my-doc           Show tree starting from 'my-doc'
  iwe tree -k doc-a -k doc-b   Show trees from multiple starting points
  iwe tree --depth 2           Show only 2 levels deep

When documents form circular references (A→B→C→A), they have no natural root.
Use -k to start from any document in the cycle:
  iwe tree -k doc-a            View cycle starting from 'doc-a'

Works great with grep to filter the tree:
  iwe tree | grep -i api       Find documents mentioning 'api'
  iwe tree -f keys | grep cli  Find documents with 'cli' in the key