docs(adapter): Update Prisma docs (#1279)

Author: iaincollins

www/docs/schemas/adapters.md

@@ -55,13 +55,13 @@ However, it should not be enabled against production databases as it may cause d
 
 ## Prisma Adapter
 
-You can also use NextAuth.js with [Prisma](https://www.prisma.io/docs/).
+You can also use NextAuth.js with the experimental adapter for [Prisma 2](https://www.prisma.io/docs/).
 
 To use this adapter, you need to install Prisma Client and Prisma CLI:
 
 ```
-npm i @prisma/client
-npm add -D @prisma/cli
+npm install @prisma/client
+npm install prisma --save-dev
 ```
 
 Configure your NextAuth.js to use the Prisma adapter:
@@ -91,7 +91,7 @@ While Prisma includes an experimental feature in the migration command that is a
 
 ### Prisma Schema
 
-Create a `schema.prisma` file similar to this one:
+Create a schema file in `prisma/schema.prisma` similar to this one:
 
 ```json title="schema.prisma"
 generator client {
@@ -179,12 +179,22 @@ datasource db {
 
 ### Generate Client
 
-Once you have saved your schema, you can run the Prisma CLI to generate the Prisma Client:
+Once you have saved your schema, use the Prisma CLI to generate the Prisma Client:
 
 ```
-npx @prisma/cli generate
+npx prisma generate
 ```
 
+To configure you database to use the new schema (i.e. create tables and columns) use the `primsa migrate` command:
+
+```
+npx prisma migrate dev --preview-feature
+```
+
+To generate a schema in this way with the above example code, you will need to specify your datbase connection string in the environment variable `DATABASE_URL`. You can do this by setting it in a `.env` file at the root of your project.
+
+As this feature is experimental in Prisma, it is behind a feature flag. You should check your database schema manually after using this option. See the [Prisma documentation](https://www.prisma.io/docs/) for information on how to use `prisma migrate`.
+
 ### Custom Models
 
 You can add properties to the schema and map them to any database column names you wish, but you should not change the base properties or types defined in the example schema.