feat(doc): explicit default values used by HikariCP (#422)

content/docs/09.administrator-guide/01.configuration/01.databases.md

@@ -103,6 +103,26 @@ Since Kestra is built with [Micronaut](https://micronaut.io) and [HikariCP](http
 | `max-lifetime`                | Long   | The maximum lifetime of a connection in the pool.                                                                              |
 | `validation-timeout`          | Long   | The maximum number of milliseconds that the pool will wait for a connection to be validated as alive.                                            |
 
+
+Here is the default HikariCP configuration:
+
+```yaml
+transaction-isolation: default
+pool-name: HikariPool-<Generated>
+connection-init-sql: null
+connection-test-query: null
+connection-timeout: 30000
+idle-timeout: 600000
+minimum-idle: 10
+initialization-fail-timeout: 1
+leak-detection-threshold: 0
+maximum-pool-size: 10 # Generates 40 connections
+max-lifetime: 1800000
+validation-timeout: 5000
+```
+
+Implementation details are accessible [here](https://github.com/brettwooldridge/HikariCP/blob/master/src/main/java/com/zaxxer/hikari/HikariConfig.java).
+
 ## Queues configuration
 
 ### `kestra.jdbc.queues`