Support for discord style subtext

[Kuuuube]

Discord supports -# for subtext. Handled the same as headers with # at the start of a line but would result in <sub>Subtext</sub>.

-# Whatever Text

Looks like this:

Reference here: https://support.discord.com/hc/en-us/articles/210298617-Markdown-Text-101-Chat-Formatting-Bold-Italic-Underline