Add issue template

.github/ISSUE_TEMPLATE.md

+#### Issue details
+
+##### Environment
+<!-- Describe how do you run Kubernetes and Dashboard. 
+     Versions of Node.js, Go etc. are needed only from developers. To get them use console:
+     $ node --version
+     $ go version
+ -->
+
+```
+Dashboard version:
+Kubernetes version:
+Operating system:
+Node.js version:
+Go version:
+```
+
+##### Steps to reproduce
+<!-- Describe all steps needed to reproduce the issue. It is a good place to use numbered list. -->
+
+##### Observed result
+<!-- Describe observed result as precisely as possible. -->
+
+##### Expected result
+<!-- Describe expected result as precisely as possible. -->
+
+##### Comments
+<!-- If you have any comments or more details, put them here. -->