Add IDCS related info to MP Security example (#4343)

forward port to 3.x

examples/microprofile/idcs/README.md

@@ -1,6 +1,41 @@
-# Helidon MP IDCS 
+# Helidon MP IDCS
 
-Example JAX-RS application with resources protected by IDCS
+This example demonstrates integration with IDCS (Oracle identity service, integrated with Open ID Connect provider) where JAX-RS application resources are protected by IDCS.
+
+## Contents
+
+This project contains two samples, one (IdcsApplication.java) and a second (ReactiveService.java). It also contains a static resource. When configured the example exposes multiple HTTP endpoints.
+
+### IDCS Configuration
+
+[This documentation](https://docs.oracle.com/en/cloud/paas/identity-cloud/uaids/oracle-identity-cloud-service.html#GUID-BC4769EE-258A-4B53-AED5-6BA9888C8275) describes basics of IDCS as well as how you can get IDCS instance.
+
+1. [Log in to the IDCS console](https://docs.oracle.com/en/cloud/paas/identity-cloud/uaids/how-access-oracle-identity-cloud-service.html) and create a new application of type "confidential app"
+2. Within  **Resources**
+    1. Create two resources called `first_scope` and `second_scope`
+    2. Primary Audience = `http://localhost:7987/"`   (ensure there is a trailing /)
+3. Within **Client Configuration**
+    1. Register a client
+    2. Allowed Grant Types = Client Credentials,JWT Assertion, Refresh Token, Authorization Code
+    3. Check "Allow non-HTTPS URLs"
+    4. Set Redirect URL to `http://localhost:7987/oidc/redirect`
+    5. Client Type = Confidential
+    6. Add all Scopes defined in the resources section
+    7. Set allowed operations to `Introspect`
+    8. Set Post Logout Redirect URL to `http://localhost:7987/loggedout`
+
+Ensure you save and *activate* the application
+
+### Application Configuration
+
+Edit application.yaml based on your IDCS Configuration
+
+1. idcs-uri  : Base URL of your idcs instance, usually something like https://idcs-<longnumber>.identity.oraclecloud.com
+2. idcs-client-id  : This is obtained from your IDCS application in the IDCS console
+3. idcs-client-secret   : This is obtained from your IDCS application in the IDCS console
+4. frontend-uri : This is the base URL of your application when run, e.g. `http://localhost:7987`
+5. proxy-host   : Your proxy server if needed
+6. scope-audience : This is the scope audience which MUST match the primary audience in the IDCS resource, recommendation is not to have a trailing slash (/)
 
 ## Build and run
 
@@ -11,6 +46,9 @@ java -jar target/helidon-examples-microprofile-security-idcs.jar
 
 Try the endpoints:
 
-```
-TODO
-```
+| Endpoint                | Description                                                                            |
+|:------------------------|:---------------------------------------------------------------------------------------|
+| `rest/login`            | Login                                                                                  |
+| `rest/scopes`           | Full security with scopes and roles (see IdcsResource.java)                            |
+| `rest/reactive`         | Protected reactive service (see application.yaml - security.web-server)                |
+| `web/resource.html`     | Protected static resource (see application.yaml - security.web-server)             |