Add content to new CoM page of Sales Handbook

Add content to new CoM page of Sales Handbook

@jbrennan1 - Thanks in advance for merging

@ejbrown71 - This MR will populate content into https://about.gitlab.com/handbook/sales/command-of-the-message as a stand-alone CoM page (to eventually replace https://about.gitlab.com/handbook/sales/#command-of-the-message). Once this is merged, you can then easily edit as you see fit. Once you are comfortable with how it looks, you/we can update the links to point to this new page. I'm happy to help.