issue templates: better version prompt

Almost no one uses `scalac` by hand, so it's not a good way to get the
current compiler version (example:
#11211), give the sbt command
instead.

Author: smarter

.github/ISSUE_TEMPLATE/bug.md

@@ -7,15 +7,10 @@ assignees: ''
 
 ---
 
-## Compiler version
-
-``` bash
-# get compiler version via command line
-scalac -version
-```
-
 ## Minimized code
 
+Using Scala (add version here, if you're not sure check with `sbt "print scalaVersion"`),
+
 ```Scala
 println("hello, world")
 ```

.github/ISSUE_TEMPLATE/crash.md

@@ -7,15 +7,10 @@ assignees: ''
 
 ---
 
-## Compiler version
-
-``` bash
-# get compiler version via command line
-scalac -version
-```
-
 ## Minimized code
 
+Using Scala (add version here, if you're not sure check with `sbt "print scalaVersion"`),
+
 ```Scala
 println("hello, world")
 ```

.github/ISSUE_TEMPLATE/other-issue.md

@@ -6,15 +6,10 @@ labels:
 assignees: ''
 ---
 
-## Compiler version
-
-``` bash
-# get compiler version via command line
-scalac -version
-```
-
 ## Minimized example
 
+Using Scala (add version here, if you're not sure check with `sbt "print scalaVersion"`),
+
 ```Scala
 println("hello, world")
 ```