book: disable content max-width so page contents uses my full screen width

doc/theme/css/general.css

@@ -159,7 +159,7 @@ h6:target::before {
 .content main {
     margin-left: auto;
     margin-right: auto;
-    max-width: var(--content-max-width);
+    /* max-width: var(--content-max-width); */
 }
 .content p { line-height: 1.45em; }
 .content ol { line-height: 1.45em; }