Use Pug template generator

blueprints/root/__init__.py

@@ -17,12 +17,12 @@ def render_tmpl(filename: str) -> str:
 
 @bp.route("/")
 def index():
-    return render_tmpl('index.html')
+    return render_tmpl('index.pug')
 
 @bp.route("/host")
 def host():
-    return render_tmpl('host.html')
+    return render_tmpl('host.pug')
 
 @bp.route("/us")
 def us():
-    return render_tmpl('us.html')
+    return render_tmpl('us.pug')