doc(cli): improve cli reference display

- fixes dunders being rendered as bold markdown
- adds the missing space before `(default:`
- monospace some known reccuring references (`pyproject.toml`, `:all`, `:pre` and `:post`)

docs/docs/reference/cli.md

@@ -2,10 +2,18 @@
 
 ```python exec="1" idprefix=""
 import argparse
+import re
 from pdm.core import Core
 
 parser = Core().parser
 
+REPLACEMENTS = {
+    "pyproject.toml": "`pyproject.toml`",
+    '":pre"': "`:pre`",
+    '":post"': "`:post`",
+    '":all"': "`:all`",
+}
+
 
 def render_parser(
     parser: argparse.ArgumentParser, title: str, heading_level: int = 2
@@ -39,9 +47,15 @@ def render_parser(
                 line = f"- {', '.join(opts)}"
             if action.metavar:
                 line += f" `{action.metavar}`"
-            line += f": {action.help}"
+            # Make dunders monospaced avoiding markdown rendering
+            help = re.sub(r"__([\w\d\_]+)__", r"`__\1__`", action.help)
+            # Style env vars: monospaced with italic prefix
+            help = re.sub(r"env var: ([A-Z_]+)", r"*env var:* `\1`", help)
+            for string, replacement in REPLACEMENTS.items():
+                help = help.replace(string, replacement)
+            line += f": {help}"
             if action.default and action.default != argparse.SUPPRESS:
-                line += f"(default: `{action.default}`)"
+                line += f" (default: `{action.default}`)"
             result.append(line)
         result.append("")