Update a Call activity
Most commonly used to update `note_html` or `outcome_id`. Some fields (`status`, `duration`, `direction`) cannot be updated for internal calls made through Close's VoIP system.
**`note_html` and `note`**: setting one overwrites the other. If both are provided, `note_html` takes precedence. `note_html` supports rich-text HTML; `note` is plaintext only.