Update issue templates (#1128)

https://blog.github.com/2018-05-02-issue-template-improvements/

.github/ISSUE_TEMPLATE/performance-problem.md

@@ -0,0 +1,23 @@
+---
+name: Performance problem
+about: Report performance problems or areas of concern
+
+---
+
+###  Timings or Profile link:
+___We ask that all timings/profiles are a link, not a screenshot. Screenshots inhibit our ability to figure out the real cause of the issue.___
+
+### Description of issue:
+___If applicable___
+
+### Plugin list:
+___All plugins running on the server___
+
+### bukkit.yml, spigot.yml, paper.yml, server.properties
+___Gist/pastebin/hastebin links___
+### Other helpful links
+___The more information we receive, the quicker and more effective we can be at finding the solution to the
+issue.___
+
+### Paper build number:
+___This can be found by running `/version` on your server. `latest` is not a proper version number; we require the output of `/version` so we can properly track down the issue.___