Add note about btree_bloat metric in panels description

Author: 0xgouda

grafana/postgres/v12/index-overview.json

@@ -250,6 +250,7 @@
         "type": "grafana-postgresql-datasource",
         "uid": "pgwatch-metrics"
       },
+      "description": "Note: The `btree_bloat` metric query filters to bloated indexes over 1 MiB by default; for large databases, you might only care about indexes over 100 MiB or so, so modify the metric accordingly in your metric configs.",
       "fieldConfig": {
         "defaults": {
           "color": {

grafana/prometheus/v12/index-overview-prometheus.json

@@ -458,7 +458,7 @@
         "type": "prometheus",
         "uid": "pgwatch-prometheus"
       },
-      "description": "",
+      "description": "Note: The `btree_bloat` metric query filters to bloated indexes over 1 MiB by default; for large databases, you might only care about indexes over 100 MiB or so, so modify the metric accordingly in your metric configs.",
       "fieldConfig": {
         "defaults": {
           "color": {