Adding a missing line of code (#232)

A line of code in the .md for Go in the euclidean algorithm was missing so I added it in

Author: Wesley-Arrington

chapters/euclidean_algorithm/euclidean.md

@@ -109,6 +109,7 @@ MainClass.java
 {% sample lang="ml" %}
 ### Ocaml
 [import, lang="ocaml"](code/ocaml/euclidean_example.ml)
+{% sample lang="go" %}
 ### Go
 [import, lang="golang"](code/go/euclidean.go)
 {% endmethod %}