fix boot dev golang course link (#842)

Author: wagslane

tutorials/learn-golang.org/en/Welcome.md

@@ -1,6 +1,6 @@
 # Welcome
 
-Welcome to the learn-golang.org interactive Go tutorial. This website is proudly supported by [Boot.dev's Learn Go course](https://www.boot.dev/courses/learn-go?promo=LEARNXORG). If you'd like to learn Golang from start to finish, [become a member and use code LEARNXORG](https://www.boot.dev/pricing?promo=LEARNXORG) for 25% off your first year!
+Welcome to the learn-golang.org interactive Go tutorial. This website is proudly supported by [Boot.dev's Learn Go course](https://www.boot.dev/courses/learn-golang?promo=LEARNXORG). If you'd like to learn Golang from start to finish, [become a member and use code LEARNXORG](https://www.boot.dev/pricing?promo=LEARNXORG) for 25% off your first year!
 
 Whether you are an experienced programmer or not, this website is intended for everyone who wishes to learn the Go programming language.