Resolve CRO - Website Quick Fixes - Add trust marks

Related to: https://gitlab.com/gitlab-com/marketing/general/issues/2305

Review apps:

https://add-trust-marks.about.gitlab.com/products/ —> redirects to /pricing, click Product in top nav

https://add-trust-marks.about.gitlab.com/pricing/

https://add-trust-marks.about.gitlab.com/sales/

https://add-trust-marks.about.gitlab.com/free-trial/

https://add-trust-marks.about.gitlab.com/webcast/gitlab-enterprise-demo/