Document GC characteristics of instant formatters

Author: ppkarwasz

src/site/antora/modules/ROOT/pages/manual/json-template-layout.adoc

@@ -1291,6 +1291,13 @@ unit          = "unit" -> (
 rounded       = "rounded" -> boolean
 ----
 
+[NOTE]
+====
+The resolvers based on the `epochConfig` expression are garbage-free.
+
+The resolvers based on the `patternConfig` expression are low-garbage and generate temporary objects only once a minute.
+====
+
 .See examples
 [%collapsible]
 ====

src/site/antora/modules/ROOT/pages/manual/pattern-layout.adoc

@@ -1607,7 +1607,9 @@ Format modifiers to control such things as field width, padding, left, and right
 
 |<<converter-date,%d +
 %date>>
-|Only the predefined date formats (`DEFAULT`, `ISO8601`, `UNIX`, `UNIX_MILLIS`, etc.) are garbage-free
+|
+The numeric formats (`UNIX` and `UNIX_MILLIS`) are garbage-free.
+The remaining formats are low-garbage and only generate temporary objects once per minute.
 
 |<<converter-encode,%enc\{pattern} +
 %encode\{pattern}>>