add issue template

Author: funbringer

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,28 @@
+<!--
+### IMPORTANT: make sure that you:
+
+- are familiar with [known limitations](https://github.com/postgrespro/pg_pathman/wiki/Known-limitations).
+- checked the [faq](https://github.com/postgrespro/pg_pathman/wiki/What-the-FAQ) for common problems.
+-->
+
+
+### Problem description
+
+Explain your problem here (it's always better to provide reproduction steps) ...
+
+
+
+### Environment
+
+<!-- Put the result of (SELECT * FROM pg_extension) below -->
+
+<!-- Put the result of (SELECT version()) below -->
+
+<!-- For Postgres Pro: put the result of (SELECT pgpro_version()) below -->
+
+<!-- For Postgres Pro: put the result of (SELECT pgpro_edition()) below -->
+
+<!-- For pg_pathman 1.4: put the result of (SELECT get_pathman_lib_version()) below -->
+
+<!-- For pg_pathman 1.5: put the result of (SELECT pathman_version()) below -->
+