update button asset to use github repo

Author: nullfunc

README.md

@@ -1,6 +1,6 @@
 # Ruby on Rails
 
-[![1-click-deploy](https://defang.io/deploy-with-defang.svg)](https://portal.defang.dev/redirect?url=https%3A%2F%2Fgithub.com%2Fnew%3Ftemplate_name%3Dsample-rails-template%26template_owner%3DDefangSamples)
+[![1-click-deploy](https://raw.githubusercontent.com/DefangLabs/defang-assets/main/Logos/Buttons/SVG/deploy-with-defang.svg)](https://portal.defang.dev/redirect?url=https%3A%2F%2Fgithub.com%2Fnew%3Ftemplate_name%3Dsample-rails-template%26template_owner%3DDefangSamples)
 
 This template is a member list project developed using Ruby on Rails, offering a starting point to help you quickly build your team management system. We have prepared all the essential files for deployment. By spending less than 10 minutes setting up the environment, as detailed in the prerequisites, and executing the commands in our step-by-step guide, your website will be ready to go live to the world!