Revert change to timestamp text

src/content/docs/logs/log-management/log-api/introduction-log-api.mdx

@@ -359,7 +359,7 @@ Some specific attributes have additional restrictions:
 * `accountId`: This is a reserved attribute name. If it is included, it will be dropped during ingest.
 * `entity.guid`, `entity.name`, and `entity.type`: These attributes are used internally to identify entities. Any values submitted with these keys in the attributes section of a metric data point may cause undefined behavior such as missing entities in the UI or telemetry not associating with the expected entities. For more information please refer to [Entity synthesis](/docs/new-relic-one/use-new-relic-one/core-concepts/what-entity-new-relic/#entity-synthesis).
 * `eventType`: This is a reserved attribute name. If it is included, it will be dropped during ingest.
-* `timestamp`: This is an numeric Unix epoch timestamp. You can define timestamps either in seconds or in milliseconds.
+* `timestamp`: Must be a Unix epoch timestamp. You can define timestamps either in seconds or in milliseconds.
 
 <Callout variant="important">
   Payloads with timestamps older than 48 hours may be dropped.