Update elasticsearch.md (fluent#1185)

Broken link leads to 404.

Signed-off-by: xogoodnow <[email protected]>

Author: xogoodnow

pipeline/outputs/elasticsearch.md

@@ -31,7 +31,7 @@ The **es** output plugin, allows to ingest your records into an [Elasticsearch](
 | Type | Type name | \_doc |
 | Logstash\_Format | Enable Logstash format compatibility. This option takes a boolean value: True/False, On/Off | Off |
 | Logstash\_Prefix | When Logstash\_Format is enabled, the Index name is composed using a prefix and the date, e.g: If Logstash\_Prefix is equals to 'mydata' your index will become 'mydata-YYYY.MM.DD'. The last string appended belongs to the date when the data is being generated. | logstash |
-| Logstash\_Prefix\_Key | When included: the value of the key in the record will be evaluated as key reference and overrides Logstash\_Prefix for index generation. If the key/value is not found in the record then the Logstash\_Prefix option will act as a fallback. The parameter is expected to be a [record accessor](../../administration/configuring-fluent-bit/classic-mode/record-accessor). |  |
+| Logstash\_Prefix\_Key | When included: the value of the key in the record will be evaluated as key reference and overrides Logstash\_Prefix for index generation. If the key/value is not found in the record then the Logstash\_Prefix option will act as a fallback. The parameter is expected to be a [record accessor](../../administration/configuring-fluent-bit/classic-mode/record-accessor.md). |  |
 | Logstash\_Prefix\_Separator | Set a separator between logstash_prefix and date.| - |
 | Logstash\_DateFormat | Time format \(based on [strftime](http://man7.org/linux/man-pages/man3/strftime.3.html)\) to generate the second part of the Index name. | %Y.%m.%d |
 | Time\_Key | When Logstash\_Format is enabled, each record will get a new timestamp field. The Time\_Key property defines the name of that field. | @timestamp |