Add missing metric <prefix>.transaction.validation_failure (#1544)

Author: renetapopova

modules/ROOT/pages/monitoring/metrics/reference.adoc

@@ -188,7 +188,7 @@ By default, database metrics include:
 
 [role=label--new-5.7]
 [[db-state-count-metrics]]
-=== Database state count metrics 
+=== Database state count metrics
 
 // label:new[Introduced in 5.7]
 
@@ -202,7 +202,7 @@ By default, database metrics include:
 |===
 
 [[db-data-metrics]]
-=== Database data metrics 
+=== Database data metrics
 
 label:deprecated[Deprecated in 5.15]
 
@@ -363,6 +363,7 @@ label:deprecated[Deprecated in 5.15]
 |<prefix>.transaction.last_closed_tx_id|The ID of the last closed transaction. (counter)
 |<prefix>.transaction.tx_size_heap|The transactions' size on heap in bytes. (histogram)
 |<prefix>.transaction.tx_size_native|The transactions' size in native memory in bytes. (histogram)
+|<prefix>.transaction.validation_failure|The total number of multi version transaction validation failures. (counter)
 |===
 
 [[db-index-metrics]]
@@ -407,9 +408,9 @@ label:deprecated[Deprecated in 5.15]
 == Metrics specific to clustering
 
 [[catchup-metrics]]
-=== CatchUp metrics
+=== Catch-up metrics
 
-.CatchUp metrics
+.Catch-up metrics
 [options="header",cols="<3m,<4"]
 |===
 |Name |Description
@@ -432,7 +433,7 @@ label:deprecated[Deprecated in 5.15]
 |===
 
 [[raft-core-metrics]]
-=== Raft core metrics 
+=== Raft core metrics
 
 label:deprecated[Deprecated in 5.0]