Update bug issue template

Author: kubukoz

.github/ISSUE_TEMPLATE/bug.md

@@ -12,6 +12,8 @@ assignees: ''
 If you're not sure what version you're using, run `print scalaVersion` from sbt
 (if you're running scalac manually, use `scalac -version` instead).
 
+If possible, check if your issue appears in the nightly version of the compiler! For example, in scala-cli, you can use `//> using scala 3.nightly` to grab the latest one.
+
 ## Minimized code
 
 <!--
@@ -20,7 +22,7 @@ This code should be self contained, compilable (with possible failures) and as s
 Ideally, we should be able to just copy this code in a file and run `scalac` (and maybe `scala`) to reproduce the issue.
 -->
 
-```Scala
+```scala
 println("hello, world")
 ```