[furo] customize CSS - code.literal nowrap & improve large table layout (#3408)

The readability can be improve with the following two changes:

Slightly increase the content width to make the engine list more readable::

    .content {
      width: 52em;    /*  instead of 46em */
    }

To avoid word wrap in bang::

    p code.literal {
      text-wrap: nowrap;
    }

Sugested-by: https://github.com/searxng/searxng/pull/3408#issuecomment-2094082144

docs/_static/searxng.css

@@ -1,3 +1,10 @@
+.content {
+  width: 52em;    /*  instead of 46em */
+}
+
+p code.literal {
+  text-wrap: nowrap;
+}
 
 aside.sidebar {
   border-color: lightsteelblue;