docs(provider): Update azure-ad-b2c.md [skip release] (#1280)

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

* Update azure-ad-b2c.md

add hint for redirection URL, otherwise difficult to find out

* Update azure-ad-b2c.md

changed .env ro .env.local as per recommendation

* Update azure-ad-b2c.md

* Update azure-ad-b2c.md

* Update azure-ad-b2c.md

* update conf in .env.local 

follow the .env guidelines

* Update azure-ad-b2c.md

* Create azure-ad-b2c.md

* Create azure-ad-b2c.md

* Update azure-ad-b2c.md

Co-authored-by: Iain Collins <me@iaincollins.com>

www/docs/providers/azure-ad-b2c.md

@@ -12,7 +12,24 @@ https://docs.microsoft.com/en-us/azure/active-directory/develop/v2-oauth2-auth-c
 https://docs.microsoft.com/en-us/azure/active-directory-b2c/tutorial-create-tenant
 
 ## Example
+- In https://portal.azure.com/ -> Azure Active Directory create a new App Registration.
+- Make sure to remember / copy
+  - Application (client) ID
+  - Directory (tenant) ID
+- When asked for a redirection URL, use http://localhost:3000/api/auth/callback/azure-ad-b2c
+- Create a new secret and remember / copy its value immediately, it will disappear.
 
+In `.env.local` create the follwing entries:
+
+```
+AZURE_CLIENT_ID=<copy Application (client) ID here> 
+AZURE_CLIENT_SECRET=<copy generated secret value here>
+AZURE_TENANT_NAME=<copy the name of the tenant here>
+AZURE_TENANT_ID=<copy the tenant id here>
+```
+
+In `pages/api/auth/[...nextauth].js` find or add the AZURE entries:
+
 ```js
 import Providers from 'next-auth/providers';
 ...
@@ -25,4 +42,5 @@ providers: [
   }),
 ]
 ...
+
 ```