Don't render non-markdown files.

muppet/output.py

@@ -8,6 +8,7 @@ import os
 import os.path
 import pathlib
 import json
+import html
 from .gather import ModuleEntry
 from jinja2 import (
     Environment,
@@ -378,7 +379,11 @@ def setup_module(base: str, module: ModuleEntry, *, path_base: str) -> None:
         pathlib.Path(os.path.join(path, name)).mkdir(exist_ok=True)
         out_path = os.path.join(path, name, 'index.html')
 
-        content = markdown(raw_content)
+        if filename.endswith('.md'):
+            content = markdown(raw_content)
+        else:
+            content = '<pre>' + html.escape(raw_content) + '</pre>'
+
         template = jinja.get_template('content.html')
         crumbs = breadcrumbs(('Environment', ''),
                              module.name,