COMPACTION_POLICY - added warning

Author: LiorKogan

content/develop/data-types/timeseries/configuration.md

@@ -125,6 +125,12 @@ Each rule is separated by a semicolon (`;`), the rule consists of multiple field
 
   Assure that there is a bucket that starts at exactly _alignTimestamp_ after the epoch and align all other buckets accordingly. Default value: 0 (aligned with the epoch). Example: if _bucketDuration_ is 24 hours, setting _alignTimestamp_ to `6h` (6 hours after the Epoch) will ensure that each bucket’s timeframe is [06:00 .. 06:00).
 
+{{% warning %}}
+On a clustered environment, if `COMPACTION_POLICY` is set, you must use [hash tags]({{< relref "/operate/oss_and_stack/reference/cluster-spec" >}}#hash-tags) for all time series key names. 
+This will force each compaction to be created in the same hash slot as its source key.
+Failure to do so can result in data not being compacted with no error messages.
+{{% /warning %}}
+
 When a compaction policy is defined, compaction rules will be created automatically for newly created time series, and their key would be set to:
 
 * If the time bucket alignment is 0: