fix(dashboard): secret keyword typo (#329)

diff --git a/charts/apisix-dashboard/templates/configmap.yaml b/charts/apisix-dashboard/templates/configmap.yaml
index c40823f..e869fbb 100644
--- a/charts/apisix-dashboard/templates/configmap.yaml
+++ b/charts/apisix-dashboard/templates/configmap.yaml
@@ -53,7 +53,7 @@
     {{- end }}
     {{- with .Values.config.authentication }}
     authentication:
-      secert: {{ .secert }}
+      secret: {{ .secret }}
       expire_time: {{ .expireTime }}
       users:
         {{- range .users }}
diff --git a/charts/apisix-dashboard/values.yaml b/charts/apisix-dashboard/values.yaml
index e29ecd3..f160222 100644
--- a/charts/apisix-dashboard/values.yaml
+++ b/charts/apisix-dashboard/values.yaml
@@ -74,7 +74,7 @@
         filePath: /dev/stdout
 
   authentication:
-    secert: secert
+    secret: secret
     expireTime: 3600
     users:
       - username: admin