[Docs] Switch to better markdown linting pre-commit hook (#21851)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

pyproject.toml

@@ -156,16 +156,6 @@ markers = [
     "optional: optional tests that are automatically skipped, include --optional to run them",
 ]
 
-[tool.pymarkdown]
-plugins.md004.style = "sublist" # ul-style
-plugins.md007.indent = 4 # ul-indent
-plugins.md007.start_indented = true # ul-indent
-plugins.md013.enabled = false # line-length
-plugins.md041.enabled = false # first-line-h1
-plugins.md033.enabled = false # inline-html
-plugins.md046.enabled = false # code-block-style
-plugins.md024.allow_different_nesting = true # no-duplicate-headers
-
 [tool.ty.src]
 root = "./vllm"
 respect-ignore-files = true