Repeat home page pattern on top-level pages

Each page under Use GitLab is currently a bulleted list (for the most part), but a table would be nicer, and would match the pattern of the top-level pages. For example:

We can start by putting the titles in a table. Let's not worry about the descriptions for now. (Maybe that can be a follow-up issue?)

Here is an example of the markdown:

| | | |
|--|--|--|
| [**Manage your organization**](../topics/set_up_organization.md) **{chevron-right}**<br><br>Description.| | |

Pages to update

• Manage your organization
• Organize work with projects
• Plan and track work
• Manage your code
• Use CI/CD to build your application
• Secure your application
• Deploy and release your application (can remove the related topics)
• Manage your infrastructure

You're welcome to play with ideas and do whatever makes sense, as long as it has somewhat of the same look and feel as the top-most pages.