Update PR template (#55)

Author: Chris Cho

.github/pull_request_template.md

@@ -11,3 +11,4 @@ Staging - <https://docs-mongodbcom-staging.corp.mongodb.com/drivers/docsworker-x
 - [ ] Did you run a spell-check?
 - [ ] 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?