Investigate whether to change unordered list sub-bullet "bullet symbols" to symbols that look different

[jafingerhut]

Original comments:

• Switching from Madoko to AsciiDoc for P4Runtime specification #510 (comment)

Andy's replyI agree it is not ideal that all levels of bullets use the same symbol as the bullet. This was a workaround for an earlier problem we encountered where if we tried to use different symbols, the font we were using did not have the appropriate level 2 and level 3 nested bullet characters in the font's table, and it used empty rectangles for them, which looks worse than using the same character for all levels of nesting (in my opinion).

Achieving different symbols for different levels of bullet nesting would require either using a different font with those symbols defined properly, or editing the font file we have to define those symbols with reasonable shapes.