updated README and added reference

README.md

diff --git a/README.md b/README.md
index 3a6aced..3560b70 100644
--- a/README.md
+++ b/README.md
@@ -296,6 +296,7 @@
   without colors.
   * *Note:* to force colored output when there is no TTY, set the `ForceColors`
     field to `true`.
+  * *Note:* to force no colored output set the `DisableColors` field to `true`
 * `logrus.JSONFormatter`. Logs fields as JSON.
 
 Third party logging formatters:

text_formatter.go

diff --git a/text_formatter.go b/text_formatter.go
index 114723d..4b93690 100644
--- a/text_formatter.go
+++ b/text_formatter.go
@@ -35,7 +35,7 @@
 
 	prefixFieldClashes(entry)
 
-	if (f.ForceColors || IsTerminal()) && !DisableColors {
+	if (f.ForceColors || IsTerminal()) && !f.DisableColors {
 		levelText := strings.ToUpper(entry.Data["level"].(string))[0:4]
 
 		levelColor := blue