improve support for `prismjs`

[BryanWilhite]

continues from https://github.com/BryanWilhite/day-path/issues/10

adding prismjs requires being careful about language names

my name	prismjs name
bash	bash, shell
c#	csharp, cs, dotnet
console	shell
cshtml	==none== https://github.com/PrismJS/prism/issues/1225
css	css
html	markup
javascript	javascript, js
json	json, webmanifest
ps1	powershell
plaintext	==default==
typescript	typescript, ts
xml	markup, html, xml, svg, mathml, ssml, atom, rss

https://prismjs.com/#supported-languages

[BryanWilhite]

see 👀 https://github.com/BryanWilhite/day-path/issues/10