Manual:$wgStyleVersion

Site customization: $wgStyleVersion
Appended in the query string of static CSS and JS to clear client side cache when changing this.
Introducido en la versión:	1.9.0 (r16992)
Deprecated in version:	1.31.0 (git #e00925d7)
Eliminado en la versión:	1.32.0 (git #eb0f44d4)
Valores permitidos:	(string)
Valor predeterminado:	(not fix)
Otras configuraciones: Alfabéticamente | Por Función

Detalles

Bump this number when changing the global style sheets and JavaScript.

It should be appended in the query string of static CSS and JS includes, to ensure that client-side caches don't keep obsolete copies of global styles.

No necesitas cambiar esto. In addition the default values are not documented, as the actual value of this setting has no significance (except to note that it will be different, and higher, in each version of MediaWiki).