.github: don't render author-facing text in ISSUE_TEMPLATE

Fixes #27914

Change-Id: Ic359a099661e959eb25d0f763ea16a6f48a3d4c7
Reviewed-on: https://go-review.googlesource.com/c/138295Reviewed-by: Andrew Bonventre <andybons@golang.org>

.github/ISSUE_TEMPLATE

-Please answer these questions before submitting your issue. Thanks!
-
+<!-- Please answer these questions before submitting your issue. Thanks! -->
 
 ### What version of Go are you using (`go version`)?
 
+<pre>
+$ go version
+
+</pre>
 
 ### Does this issue reproduce with the latest release?
 
 
+
 ### What operating system and processor architecture are you using (`go env`)?
 
+<details><summary><code>go env</code> Output</summary><br><pre>
+$ go env
+
+</pre></details>
 
 ### What did you do?
 
+<!--
 If possible, provide a recipe for reproducing the error.
 A complete runnable program is good.
 A link on play.golang.org is best.
+-->
+
 
 
 ### What did you expect to see?
 
 
+
 ### What did you see instead?