Make value key its own column when rendering decision point examples

[ahouseholder]

This PR modifies the behavior when we render decision points as markdown tables. Instead of having Name (key), now it will render Name and Key into separate columns.

Before:

After:

Copilot Summary

This pull request updates the markdown table formatting in the src/ssvc/doc_helpers.py file to improve clarity and completeness. The changes modify both the table row template and the table header to include a separate column for the key of each value.

Markdown table formatting improvements:

• Changed the MD_TABLE_ROW_TEMPLATE to include a separate "Key" column, so each row now displays the value's name, key, and definition individually.
• Updated the markdown table header and alignment to add the "Key" column, ensuring the header matches the new row format.

[sei-vsarvepalli]

👍