I would like to propose two new rules for markdownlint that are currently implemented in my own repository:

1. Math blocks should be surrounded by blank lines ：This rule ensures that math blocks (delimited by $$ ... $$) have blank lines before and after them, improving readability and consistency.

2. Headings should not be fully emphasized ：This rule prevents headings from being composed entirely of emphasized text (e.g., ## **bold** or ## _italic_), which can reduce clarity or hinder accessibility. Similar issue: Proposal: disallow formatting in headings #1608

I believe these rules could benefit the markdownlint community by promoting best practices in markdown documents. Please let me know if you would consider including these rules, or if there are any requirements or guidelines I should follow when proposing new rules.