DOCSP-48938: Add PR checklist item for checking page titles (#249)

Author: mcmorisi

.github/pull_request_template.md

@@ -14,3 +14,4 @@ JIRA - <https://jira.mongodb.org/browse/DOCSP-NNNNN>
 - [ ] Did you run a grammar-check?
 - [ ] Are all the links working?
 - [ ] Are the [facets and meta keywords](https://wiki.corp.mongodb.com/display/DE/Docs+Taxonomy) accurate?
+- [ ] Are the page titles greater than 20 characters long and [SEO relevant](https://docs.google.com/spreadsheets/d/1Wkt0-5z04KmcMNscN5bjUKnzwWAtMq9VESp-Lz6r2o8/edit?usp=sharing)?