changelog: update tag_cardinality_limit cache_size_per_key fragment

Author: ArunPiduguDD

changelog.d/tag_cardinality_per_tag_cache_size.enhancement.md

@@ -1,3 +1,3 @@
-Adds support for specifying a `cache_size_per_key` in per-tag override configuration options when in probabilistic mode. Previously, even if a per-tag `value_limit` override is specified, it would still inherit the same `cache_size_per_key` as the enclosing global/per-metric configuration, which can lead to a higher false positive rate if the per-tag `value_limit` is higher than the enclosing global/per-metric `value_limit`. The field is optional and falls back to the enclosing per-metric or global cache size when omitted (ignored when `mode` is `exact`).
+Adds a per-tag `cache_size_per_key` option to configuration options in probabilistic mode. Previously, per-tag overrides always inherited the bloom filter cache size from the enclosing config, which could cause a higher false positive rate when the per-tag `value_limit` is higher than the global or per-metric `value_limit`. When omitted, the cache size value from the enclosing config is used. Only valid in `probabilistic` mode — using it in `exact` mode will cause a configuration error.
 
 authors: ArunPiduguDD