change file type

Author: thepriefy

.github/ISSUE_TEMPLATE.md renamed to .github/ISSUE_TEMPLATE

@@ -14,4 +14,4 @@ Any other information you want to share that is relevant to the issue being repo
 #### Technical details:
 
 * smtpapi-nodejs Version: master (latest commit: [commit number])
-* Node.js Version: 4.x.x
+* Node.js Version: 4.x.x