fix All Projects table on Distribution team page

Why is this change being made?

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The table under the All Projects heading on the Distribution team's page in the handbook is displaying raw markdown because it's missing one of the columns in the divider row between the table header row and content rows.

I've added a third column to the divider row so it gets formatted as an HTML table.

When a markdown table doesn't get get converted to an HTML table all the line breaks get removed and it's unreadable. This fixes that issue.

• fix All Projects table on Distribution team page

Author and Reviewer Checklist

Please verify the check list and ensure to tick them off before the MR is merged.

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
  • Copy/paste the Slack conversation to document it for later, or upload screenshots. Verify that no confidential data is added, and the content is SAFE
• Assign reviewers for this MR to the correct Directly Responsible Individual/s (DRI)
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the Maintained by section on the page being edited
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  • The when to get approval handbook section explains the workflow in more detail
• For transparency, share this MR with the audience that will be impacted.
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