Use details tag around code backticks for 'helm get' output in issue …

…template

The output can be quite long and long output clutters up the issue description.

Note that the empty line is necessary in order for the code to be parsed correctly (see dear-github/dear-github#166 (comment) for details).

.github/ISSUE_TEMPLATE/bug_report.md

@@ -20,9 +20,14 @@ e.g. `helm get elasticsearch` (replace `elasticsearch` with the name of your hel
 
 *If you find some secrets in plain text in `helm get release` output you should use [Kubernetes Secrets](https://kubernetes.io/docs/concepts/configuration/secret/) to managed them is a secure way (see [Security Example](https://github.com/elastic/helm-charts/blob/master/elasticsearch/examples/security/security.yml#L23-L38)).*
 
+<details>
+<summary>Output of helm get release</summary>
+
 ```
 ```
 
+</details>
+
 **Describe the bug:**
 
 **Steps to reproduce:**