Rename CESG device guidance slug
user
```ruby
OLD_SLUG = 'end-user-devices-security-guidance--2'
NEW_SLUG = 'end-user-devices-security-guidance'

document = Document.find_by_slug(OLD_SLUG)
document.update_attribute(:slug, NEW_SLUG)

router = GdsApi::Router.new(Plek.current.find('router-api'))
router.add_redirect_router("/government/collections/#{OLD_SLUG}",
                           'exact',
                           "/government/collections/#{NEW_SLUG}")
```
assistant