updated the docs

Author: ab-ghosh

docs/cmd/tkn_pipeline_logs.md

@@ -40,6 +40,7 @@ Show logs for given Pipeline and PipelineRun:
   -h, --help         help for logs
   -L, --last         show logs for last PipelineRun
       --limit int    lists number of PipelineRuns (default 5)
+      --prefix       prefix each log line with the log source (task name and step name) (default true)
   -t, --timestamps   show logs with timestamp
 ```
 

docs/man/man1/tkn-pipeline-logs.1

@@ -39,6 +39,10 @@ Show Pipeline logs
 \fB\-\-limit\fP=5
     lists number of PipelineRuns
 
+.PP
+\fB\-\-prefix\fP[=true]
+    prefix each log line with the log source (task name and step name)
+
 .PP
 \fB\-t\fP, \fB\-\-timestamps\fP[=false]
     show logs with timestamp