Add PR template (#5)

Author: di

.github/PULL_REQUEST_TEMPLATE/new-trove-classifier.md

@@ -0,0 +1,22 @@
+---
+name: New Trove Classifier
+title: New Trove Classifier
+about: Request a new trove classifier
+labels: classifier request
+
+---
+
+Request to add a new Trove classifier.
+
+## The name of the classifier(s) you would like to add
+
+<!-- Replace the following with the name of your classifier -->
+* `Your :: Trove :: Classifier`
+
+## Why do you want to add this classifier?
+<!--
+    Include a brief explanation to justify your request.
+    Why do the current classifiers not meet your need?
+    How many projects do you expect to use this new classifier?
+    If you are requesting multiple classifiers, why do you need more than one?
+-->