Add some possibility to create DITA superscript (sup) and subscript (sub) elements

[raducoravu]

Maybe using "^" and "~" to surround those pieces of text.
Something like:

      32^nd^ H~2~O

[raducoravu]

Right now for this markdown content:

        # Header 1
        
        1. ^p^p

I get in the DITA content:

  No renderer configured for com.vladsch.flexmark.superscript.Superscript

[jgranduel]

Same issue today.
(The markdown was created by a transformation from a .docx document with pandoc which supports this notation.)

[raducoravu]

As a workaround you can use HTML style tags for sup and sub, they seemed to work from what I tested. Entity references seem to work also: https://www.oxygenxml.com/forum/post57825.html#p57825

[raducoravu]

+1 another one of our end users asked for this.