added PR template

PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,9 @@
+If you are adding something, explain briefly why do you think that web app is **awesome**.
+
+If you are changing something, explain briefly why that change was needed.
+
+Apart from that, go through the following checkpoints --
+
+- [ ] I have read the [Contribution guidelines](https://github.com/aviaryan/awesome-no-login-web-apps/blob/master/CONTRIBUTING.md) and I am confident that my PR is suitable 
+for this project. 
+- [ ] I have edited the PR title from "update README.md" to something meaningful.