Update references to externals

[taylortom]

This weren't carried across when we switched to jsdoc.

The following have been renamed:

• ClientServer -> external:express~Request
• ServerResponse -> external:express~Response
• net-Server -> external:http~Server

The following need the external: prefix:

• express~App
• express~Router
• mongodb~Collection
• mongodb~MongoClient
• mongodb~ObjectId
• nodemailer~Transport

[taylortom]

Done