Incomplete Markdown documentation

[Petrox]

• Full list of supported emojis (colon markup like 👍 💯 🥇 ) are missing. (a link would be enough of course)
• There is no example or description on how to add intentional line break in a table cell
• No mention of non breaking space to avoid linebreaks
• The documentation briefly mentions extension_set, without any description of what the four options are, what are the differences and where are the full specs of the extensions.

For example: google github_web markdown leads to

https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax

Following that document one could expect a Table Of Contents to appear as in:
"When you use two or more headings, GitHub automatically generates a table of contents that you can access by clicking within the file header. "

Since the documentation does not specify what to expect from any of the extensions I don't know what to expect from any symbol not directly mentioned in the example.

[FeodorFitsner]

Would you like to do a PR with your corrections?

[Petrox]

I would do that of course, but I don't have the info that is not in the docs (and I'm not deep into flet or flutter either) so unfortunately my contribution is mostly limited to pointing out the missing info and maybe typos.