Add an issue template

ISSUE_TEMPLATE.md

@@ -0,0 +1,6 @@
+Please consider submitting the following information:
+
+* Library setup method: file, Carthage, CocoaPods or Swift Package Manager.
+* Version of the library, if known. Example: 8.0.
+* Xcode version. Example: 8.3.3.
+* iOS version. Example: 10.3.2.