Add a GitHub issue template to help contributors confirm their issue …

…is with bootsnap

.github/issue_template.md

@@ -0,0 +1,22 @@
+### I made sure the issue is in bootsnap
+
+<!-- Bootnsap is very often wrongly blamed for application problems,
+  try setting DISABLE_BOOTSNAP=1, if your problem persist it's unlikely
+  to be caused by bootsnap -->
+
+### Steps to reproduce
+<!-- If possible, tell us how we can reproduce the issue ourselves -->
+
+### Expected behavior
+<!-- Tell us what should happen -->
+
+### Actual behavior
+<!-- Tell us what happens instead -->
+
+### System configuration
+
+**Bootsnap version**:
+
+**Ruby version**:
+
+**Rails version**: <!-- If applicable -->