v2.2 theme-Jonas

主题加黑, 字体缩小

add title2-4 number display instead of symbol

1级标题展示为符号"❀";
2到4级标题会展示数字标号, 自动级联;
5和6级标题展示符号"❃"和"۞".

v1.2

Merge branch 'main' of https://github.com/Wolfxin/Typora-theme-jonas

merge and ignore the file README.md