Add shell completion generation

README.md

@@ -86,9 +86,11 @@ metadata from an authorized peer over Iroh.
 
 The bootstrap implementation provides:
 
-- `geth guide [init|owner-setup|enrollment|keys|overlay|service|smoke-test]` for
+- `geth guide [init|owner-setup|enrollment|keys|overlay|service|completions|smoke-test]` for
   embedded workflow help, including `--admin-key` / `--signing-key` setup
   examples
+- `geth completions <bash|zsh|fish|powershell|elvish>` for shell completion
+  scripts generated from the live CLI command tree
 - `geth init`
 - `geth init --admin-key <public-key> --signing-key <private-key> --node-name <name>`
 - `geth daemon run`