Update oauth2_pocketid.adoc

PocketID now requires to explicitly include the `openid` scope in the `scopes` list. PocketID will strictly block user information queries with a `403 Forbidden` if this scope is missing.

docs/modules/ROOT/pages/security/oauth2_pocketid.adoc

@@ -39,6 +39,7 @@ authOAuth2Providers:
     clientId: "[REDACTED]"
     clientSecret: "[REDACTED]"
     scopes:
+      - openid
       - profile
       - email
     usernameField: preferred_username
@@ -52,4 +53,4 @@ actions:
 
 == Pocket ID config
 
-image::pocketid.png[]
+image::pocketid.png[]