doc updates, and relabel ReportMethod

in the Logrus context it's the caller, so use that internally.  Label
stays as 'method' since in the context of the log event that seems more
correct.

logger.go

@@ -24,7 +24,7 @@ type Logger struct {
 	Formatter Formatter
 
 	//Flag for whether to log caller info (off by default)
-	ReportMethod bool
+	ReportCaller bool
 
 	// The logging level the logger should log at. This is typically (and defaults
 	// to) `logrus.Info`, which allows Info(), Warn(), Error() and Fatal() to be
@@ -75,7 +75,7 @@ func New() *Logger {
 		Formatter:    new(TextFormatter),
 		Hooks:        make(LevelHooks),
 		Level:        InfoLevel,
-		ReportMethod: false,
+		ReportCaller: false,
 	}
 }