Minor - P4 There are various places in the docs where ObjectId is spelled as 'ObjectID'. It should probably be standardized to ObjectId across all the docs.
$ grep -lrI "ObjectID" * draft/core/storage-viz.txt draft/tutorial/inserting-documents-into-a-sharded-collection.txt locale/pot/core/gridfs.pot locale/pot/core/index-single.pot locale/pot/core/sharding-shard-key.pot locale/pot/core/indexes-introduction.pot locale/pot/faq/developers.pot locale/pot/faq/sharding.pot locale/pot/reference/glossary.pot locale/pot/reference/gridfs.pot locale/pot/reference/method/db.collection.save.pot locale/pot/reference/method/cursor.sort.pot locale/pot/reference/operator/aggregation/sort.pot locale/pot/reference/limits.pot locale/pot/reference/bson-types.pot locale/pot/reference/command/nav-diagnostic.pot source/core/indexes-introduction.txt source/core/gridfs.txt source/core/sharding-shard-key.txt source/faq/sharding.txt source/includes/ref-toc-command-diagnostic.yaml source/includes/fact-sort-order.rst source/reference/glossary.txt source/reference/sql-comparison.txt source/reference/method/db.collection.save.txt source/reference/limits.txt source/reference/gridfs.txt