Enhancement: Use white background.

This change will use white, instead of transparent color background to make the text on the resume more readable when user views the README.md file in night mode.

Fix: billryan#64

README.md

@@ -27,9 +27,9 @@ An elegant \LaTeX\ résumé template, compiled with \XeLaTeX. Inspired by
 
 ### Sample Output
 
-![English](https://user-images.githubusercontent.com/1292567/62409353-3fecfc00-b608-11e9-8e83-84962912c956.png)
-![English with photo](https://user-images.githubusercontent.com/1292567/62409351-3f546580-b608-11e9-9f6d-d232a68c5451.png)
-![简体中文](https://user-images.githubusercontent.com/1292567/62409352-3fecfc00-b608-11e9-8d9e-76243ca3052a.png)
+![English](https://user-images.githubusercontent.com/25968335/131621921-65ab1862-1f56-47ef-9d58-8d5149bec841.png)
+![English with photo](https://user-images.githubusercontent.com/25968335/131621960-1cafb3c2-114b-4e90-8b04-bd9b949a6e9d.png)
+![简体中文](https://user-images.githubusercontent.com/25968335/131621980-c004f2a6-4199-4676-8a97-5d2cb165402f.png)
 
 - [English PDF](https://github.com/billryan/resume/files/3463503/resume.pdf)
 - [English with photo PDF](https://github.com/billryan/resume/files/3463501/resume_photo.pdf)