Adds PULL_REQUEST_TEMPLATE.md to follow recommended community standards

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,26 @@
+Thank you for contributing to Apache OpenNLP Models.
+
+In order to streamline the review of the contribution we ask you
+to ensure the following steps have been taken:
+
+### For all changes:
+- [ ] Is there a JIRA ticket associated with this PR? Is it referenced 
+     in the commit message?
+
+- [ ] Does your PR title start with OPENNLP-XXXX where XXXX is the JIRA number you are trying to resolve? Pay particular attention to the hyphen "-" character.
+
+- [ ] Has your PR been rebased against the latest commit within the target branch (typically main)?
+
+- [ ] Is your initial contribution a single, squashed commit?
+
+### For code changes:
+- [ ] Have you ensured that the full build works via mvn clean install at the root folder?
+- [ ] If adding new dependencies to the code, are these dependencies licensed in a way that is compatible for inclusion under [ASF 2.0](http://www.apache.org/legal/resolved.html#category-a)? 
+- [ ] If applicable, have you updated the LICENSE file, including the main LICENSE file in opennlp folder?
+- [ ] If applicable, have you updated the NOTICE file, including the main NOTICE file found in opennlp folder?
+
+### For documentation related changes:
+- [ ] Have you ensured that format looks appropriate for the output in which it is rendered?
+
+### Note:
+Please ensure that once the PR is submitted, you check GitHub Actions for build issues and submit an update to your PR as soon as possible.