Update issue templates

Author: ivan-hc

.github/ISSUE_TEMPLATE/issue.md

@@ -0,0 +1,12 @@
+---
+name: Issue
+about: " Generic issue"
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+Before opening any issue, we assume you have read the CONTRIBUTING page
+
+https://github.com/Portable-Linux-Apps/Portable-Linux-Apps.github.io/blob/main/CONTRIBUTING.md