change qr code (#562)

diff --git a/docs/.vuepress/public/tool-playground-qrcode.png b/docs/.vuepress/public/tool-playground-qrcode.png
index bdfd4b2..83540eb 100644
--- a/docs/.vuepress/public/tool-playground-qrcode.png
+++ b/docs/.vuepress/public/tool-playground-qrcode.png
Binary files differ