Update PULL_REQUEST_TEMPLATE.md

Added instructions as comments

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,17 +1,17 @@
-Thank you for sending your pull request. But first, have you included
+<!-- Thank you for sending your pull request. But first, have you included
 unit tests, and is your code PEP8 conformant? [More details](https://github.com/freqtrade/freqtrade/blob/develop/CONTRIBUTING.md)
-
+-->
 ## Summary
 
-Explain in one sentence the goal of this PR
+<!-- Explain in one sentence the goal of this PR -->
 
 Solve the issue: #___
 
 ## Quick changelog
 
-- <change log 1>
-- <change log 1>
+- <!-- <change log 1> -->
+- <!-- <change log 1> -->
 
 ## What's new?
 
-*Explain in details what this PR solve or improve. You can include visuals.* 
+<!-- Explain in details what this PR solve or improve. You can include visuals. -->