[IMP] CRM: Inactive lost leads

[pabr-odoo]

Task: https://www.odoo.com/odoo/my-tasks/4013046

Adding as small note admonition explaining how to mark an inactive lead as lost.

[robodoo]

[pabr-odoo]

Hey @StraubCreative tagging you in for first review on this small addition when you get the chance. Thanks!