* feat: ApolloServer is created and exported by all variants
* docs: add initial docs around exporting ApolloServer
* feat: export gql from integrations
* docs: change apollo-server examples to use express with registerServer
* server: remove registerExpressServer
* core, docs: comment functions, fix api reference, context creation more like middleware args
* docs: fix integrationed typo
* Bury Best Practices, for the time being.
* Bury Schema, but leave it on disk.
* Introduce new Querying section.
* Move "Why Apollo Server?" into "Index".
* ...to be refined.
* Remove no-longer-helpful "Getting Started" from "Index".
cc @stubailo @evans @peggyrayzis @JakeDawkins @unicodeveloper @jbaxleyiii
While the `gql` tag is not currently _required_, it does make it easier to
implement additional, development-friendly functionality in the future.
For example, it could avoid the need to question whether a string literal is
actually using Schema Definition Language (SDL) and avoid the need to
look for context clues.
By implementing these suggestions now, we can avoid the need to ask
developers to refactor in the future.
