Minor updates to people page

[ctubbsii]

• Ensure HTML table element IDs are unique for both Committer tables
• Update name of first Committer table, so the order of "Committer" and "PMC" matches the order on the second table (with "Committer" shown first) and to make it clear that the table represents the current PMC
• Create new committers style class and use that instead of table IDs for the JavaScript that turns Apache IDs into links; also update corresponding comment to be clear that committers have Apache IDs, not PMC members.
• Minor fixes to table markdown formatting vertical bars