Docs: Update gauge.md (#22637)

Update the hierarchy of gauge.md

docs/sources/features/panels/gauge.md

@@ -21,8 +21,8 @@ The Gauge is a single value panel that can repeat a gauge for every series, colu
 * Calc
   * Specify calculation / reducer function. Since this panel is designed to only show a single value Grafana needs to
     know how to reduce a fields many values to a single value.
-** Labels - Controls if thresholds values are shown.
-** Markers - Controls if a thresholds band is shown outside the inner gauge value band.
+* Labels - Controls if thresholds values are shown.
+* Markers - Controls if a thresholds band is shown outside the inner gauge value band.
 
 ## Field