Add docs for per capp logging

This is related to wso2/micro-integrator#3429

en/docs/develop/monitoring-capp-level-logs.md

@@ -0,0 +1,43 @@
+# Monitoring Composite Application-Level Logs
+
+The advantage of having per-composite application logs is that it is very easy to analyze/monitor what went wrong in this particular composite application (integration) by looking at the logs. 
+
+## Enabling log4j2 for capp logging
+
+Follow the instructions below to enable log4j2 logs for a sample composite application (named `HelloWorldCompositeExporter`).
+
+1.  Open up the `log4j2.properties` file (stored in the `<MI_HOME>/conf` directory. 
+2.  Let's modify the layout pattern of a new or existing appender for the `HelloWorldCompositeExporter` composite application by adding the following section.
+
+    ```bash
+    %X{Artifact-Container}
+     ```
+    For exmaple:
+    ```bash
+    # CARBON_LOGFILE is set to be a DailyRollingFileAppender using a PatternLayout.
+    appender.CARBON_LOGFILE.type = RollingFile
+    appender.CARBON_LOGFILE.name = CARBON_LOGFILE
+    appender.CARBON_LOGFILE.fileName = ${sys:logfiles.home}/wso2carbon.log
+    appender.CARBON_LOGFILE.filePattern = ${sys:logfiles.home}/wso2carbon-%d{MM-dd-yyyy}.log
+    appender.CARBON_LOGFILE.layout.type = PatternLayout
+    appender.CARBON_LOGFILE.layout.pattern = [%d] %5p {%c}  |%X{Artifact-Container}| - %m%ex%n
+    appender.CARBON_LOGFILE.policies.type = Policies
+    appender.CARBON_LOGFILE.policies.time.type = TimeBasedTriggeringPolicy
+    appender.CARBON_LOGFILE.policies.time.interval = 1
+    appender.CARBON_LOGFILE.policies.time.modulate = true
+    appender.CARBON_LOGFILE.policies.size.type = SizeBasedTriggeringPolicy
+    appender.CARBON_LOGFILE.policies.size.size=10MB
+    appender.CARBON_LOGFILE.strategy.type = DefaultRolloverStrategy
+    appender.CARBON_LOGFILE.strategy.max = 20
+    appender.CARBON_LOGFILE.filter.threshold.type = ThresholdFilter
+    appender.CARBON_LOGFILE.filter.threshold.level = DEBUG
+    ```
+
+3. Save the `log4j2.properties` file.
+
+A sample log output:
+
+    ```bash
+    [2024-07-11 08:34:36,970]  INFO {org.apache.synapse.mediators.builtin.LogMediator}  |[ Deployed From Artifact Container: HelloWorldCompositeExporter ] | - {api:testAPI} SampleLog = started
+    [2024-07-11 08:34:46,110]  INFO {org.apache.synapse.core.axis2.TimeoutHandler}  |[ Deployed From Artifact Container: HelloWorldCompositeExporter ] | - This engine will expire all callbacks after GLOBAL_TIMEOUT: 120 seconds, irrespective of the timeout action, after the specified or optional timeout
+    ```

en/mkdocs.yml

@@ -333,6 +333,7 @@ nav:
       - Debug Integrations:
           - Mediation Debugging: develop/debugging-mediation.md
           - Use Wire Logs: develop/using-wire-logs.md
+          - Monitor Composite Application-Level Logs: develop/monitoring-capp-level-logs.md
           - Monitor Service-Level Logs: develop/monitoring-service-level-logs.md
           - Monitor API-Level Logs: develop/monitoring-api-level-logs.md
           - Endpoint Trace: develop/endpoint-trace-logs.md