I think your q means for making posts via github pages, does one need to know more than markdown? If so:
You usually need to add some metadata (often it’s “yaml frontmatter”), but that’s just like author, date, etc. Besides that you don’t need to know anything more than markdown to make posts (at least using jekyll or hugo; two of the static site generators that github pages supports).
If you want to customize the template, or do more advanced stuff, then you need to know at least a bit about the relevant template language, html, and css.
You can see the code for Anne’s github pages site here: sicp-exercises/_config.yml at main · aelanteno/sicp-exercises · GitHub (well, this is actually the config file, but it shows you how simple it is). here’s a file with code that shows syntax highlighting (also mentioned below): https://raw.githubusercontent.com/aelanteno/sicp-exercises/main/exercise-1.10.md
From https://xertrov.github.io/fi, here’s an example of one of my posts (just plain markdown): fi/2020-09-02-analysing-lw-replies-for-social-dynamics.md at master · XertroV/fi · GitHub
You can hit the ‘raw’ button on the top right of the file to shown the plaintext version.
Most static site generators already support syntax highlighting when you use github flavored markdown with code fences, like this:
(lambda (a x) (+ a x))
or (for python)
x = 1
It seems to work on discorse, too. IDK about scheme but this is python:
def sum_some_ints(xs: List[int]) -> int:
return 0 if len(xs) == 0 else xs + sum_some_ints(xs[1:])
Though not every language is well supported on discorse – static site generators are usually better. e.g., haskell:
data TrafficLight = Green | Red | Yellow
canGo :: TrafficLight -> Boolean
canGo Green = True
canGo _ = False