Merge branch '34955-document-why-the-nan-values-are-excluded-from-monitor-charts' into 'master'

Document why the `NaN` values are excluded from monitor charts.

Closes #34955

See merge request gitlab-org/gitlab!20347

app/assets/javascripts/helpers/monitor_helper.js

@@ -7,6 +7,7 @@
 export const makeDataSeries = (queryResults, defaultConfig) =>
   queryResults
     .map(result => {
+      // NaN values may disrupt avg., max. & min. calculations in the legend, filter them out
       const data = result.values.filter(([, value]) => !Number.isNaN(value));
       if (!data.length) {
         return null;

app/assets/javascripts/monitoring/components/charts/anomaly.vue

@@ -66,6 +66,7 @@ export default {
         const values = query.result[0] ? query.result[0].values : [];
         return {
           label: query.label,
+          // NaN values may disrupt avg., max. & min. calculations in the legend, filter them out
           data: values.filter(([, value]) => !Number.isNaN(value)),
         };
       });