Added issue template

Author: sanderv32

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,18 @@
+The issue will be closed without any reasons if it does not satisfy any of following requirements:
+
+1. Please speak English.
+2. Please check the Gogs issues if this is not a Gogs issue.
+2. Please take a moment to search that an issue doesn't already exist.
+3. Please give all relevant information below for bug reports; incomplete details considered invalid report.
+4. Please take some time to investigate the problem yourself; for example click the `Test delivery` button and post the JSON output.
+
+**You MUST delete above content including this line before posting**
+
+- Gogs version (or commit ref):
+- Jenkins version:
+- Jenkins modules used in combination with gogs-webhook-plugin:
+- JSON Output of webhook:
+
+## Description
+
+...