Using a word Weave does not recognise

Writes `3 groups` instead of `3 rooms`. Only `rooms` and `per room` are accepted, so the meeting plan stays unambiguous.

The pattern

---
weave-script-version: 1
---

# Three groups <!-- breakouts: 3 groups -->

Weave only recognises `rooms` and `per room` for breakouts. Words like
`groups` or `teams` look reasonable but they're not part of the format, so
Weave asks you to rewrite the line.

What Weave sees

Weave can't read this file. Here is the message it shows so you know what to fix.

{
  "code": "invalid-breakouts",
  "message": "Cannot read breakouts \"3 groups\". Accepted forms: \"N rooms\" or \"N per room\"."
}