Allow filtering symbols by math class in the General Symbols page

[MDLC01]

Description

In the General Symbol documentation page, allow filtering symbols by math class.

Currently, this can be achieved by adding the following CSS rule to the page, (where <class> is replaced by the class). Of course, this is less than user friendly.

.symbol-grid li:not([data-math-class="<class>" i]) {
  display: none !important;
}

Use Case

Finding symbols more easily when you don't know what you are looking for exactly, but want, e.g., a new notation for a relation. For example, this may be useful by the kind of person who defines many relation, such as in typst/typst#6028.