Articles without heading/topic list

[tacitonic]

• https://make.wordpress.org/docs/style-guide/language-grammar/possessives/
• https://make.wordpress.org/docs/style-guide/punctuation/parentheses/
• https://make.wordpress.org/docs/style-guide/language-grammar/articles/

[dilipom13]

Hello @tacitonic

Opened #39 for this.

The topic list wasn't showing on those three pages because the sections used bold text instead of H2 headings. Added proper ## headings to possessives, articles, and parentheses.

Please review it.

Thank you.