Polish the doc of log feature (#6772)

docs/en/setup/backend/backend-fetcher.md

@@ -91,10 +91,11 @@ kafka-fetcher:
     bootstrapServers: ${SW_KAFKA_FETCHER_SERVERS:localhost:9092}
 ```
 
-`skywalking-segments`, `skywalking-metrics`, `skywalking-profile`, `skywalking-managements` and `skywalking-meters` topics are required by `kafka-fetcher`.
+`skywalking-segments`, `skywalking-metrics`, `skywalking-profile`, `skywalking-managements`, `skywalking-meters`
+and `skywalking-logs` topics are required by `kafka-fetcher`.
 If they do not exist, Kafka Fetcher will create them in default. Also, you can create them by yourself before the OAP server started.
 
-When using the OAP server automatical creation mechanism, you could modify the number of partitions and replications of the topics through the following configurations:
+When using the OAP server automatic creation mechanism, you could modify the number of partitions and replications of the topics through the following configurations:
 
 ```yaml
 kafka-fetcher:

docs/en/setup/backend/log-analyzer.md

@@ -1,6 +1,22 @@
+# Log Collecting And Analysis
+
+## Collecting
+There are various ways to collect logs from application.
+
+### Java agent's toolkits
+Java agent provides toolkit for 
+[log4j](../service-agent/java-agent/Application-toolkit-log4j-1.x.md),
+[log4j2](../service-agent/java-agent/Application-toolkit-log4j-2.x.md), 
+[logback](../service-agent/java-agent/Application-toolkit-logback-1.x.md) 
+to report logs through gRPC with automatic injected trace context.
+
+[SkyWalking Satellite sidecar](https://github.com/apache/skywalking-satellite) is a recommended proxy/side to
+forward logs including to use Kafka MQ to transport logs. When use this, need to open [kafka-fetcher](backend-fetcher.md#kafka-fetcher).
+
+
 ## Log Analyzer
 
-Log analyzer supports native log data. OAP could use Log Analysis Language to
+Log analyzer of OAP server supports native log data. OAP could use Log Analysis Language to
 structurize log content through parse, extract, and save logs. 
 Also the analyzer leverages Meter Analysis Language Engine for further metrics calculation.
 

docs/menu.yml

@@ -127,7 +127,7 @@ catalog:
             path: "/en/setup/backend/dynamic-config"
           - name: "Uninstrumented Gateways"
             path: "/en/setup/backend/uninstrumented-gateways"
-          - name: "Apdex threshold"
+          - name: "Apdex Threshold"
             path: "/en/setup/backend/apdex-threshold"
           - name: "Service Grouping"
             path: "/en/setup/backend/service-auto-grouping"
@@ -139,7 +139,7 @@ catalog:
             path: "/en/setup/backend/backend-meter"
           - name: "Spring Sleuth Metrics Analysis"
             path: "/en/setup/backend/spring-sleuth-setup"
-          - name: "Log Analyzer"
+          - name: "Log Collecting And Analysis"
             path: "/en/setup/backend/log-analyzer"
           - name: "Infrastructure Monitoring"
             path: "/en/setup/backend/backend-infrastructure-monitoring"