Clarify that on Neo4j startup all pagecache warmup activity results in pagefaults (#1164)

Cherry-picks #1065

Author: renetapopova

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

@@ -195,7 +195,7 @@ By default, database metrics include:
 |<prefix>.page_cache.pins|The total number of page pins executed by the page cache. (counter)
 |<prefix>.page_cache.evictions|The total number of page evictions executed by the page cache. (counter)
 |<prefix>.page_cache.evictions.cooperative|The total number of cooperative page evictions executed by the page cache due to low available pages. (counter)
-|<prefix>.page_cache.page_faults|The total number of page faults happened in the page cache. If this continues to rise over time, it could be an indication that more page cache is needed. (counter)
+|<prefix>.page_cache.page_faults|The total number of page faults in the page cache. If this count keeps increasing over time, it may indicate that more page cache is required. However, note that when Neo4j Enterprise starts up, all page cache warmup activities result in page faults. Therefore, it is normal to observe a significant page fault count immediately after startup. (counter)
 |<prefix>.page_cache.page_fault_failures|The total number of failed page faults happened in the page cache. (counter)
 |<prefix>.page_cache.page_cancelled_faults|The total number of canceled page faults happened in the page cache. (counter)
 |<prefix>.page_cache.hits|The total number of page hits happened in the page cache. (counter)