docs: Prevent text-wrap for span.pre in user guide citheme.css

Add span.pre to span.std to prevent text-wrap in user guide citheme.css

Author: obozdag

user_guide_src/source/_static/css/citheme.css

@@ -245,7 +245,8 @@ html.writer-html5 .rst-content dl[class]:not(.option-list):not(.field-list):not(
     background-color: #fffff0;
 }
 
-span.std {
+span.std,
+span.pre {
     text-wrap: nowrap;
 }