update documentation with github login

docs/manual/docs/GN4-Integration/index.md

@@ -1,6 +1,52 @@
 # GeoNetwork 5 Integration with GeoNetwork 4 {#toc}
 
-There are two main ways handle authentication between GN5 and GN4.
+During the development of GN5, GN4 will be used for some of the GN functionality.  GN5 will route some
+requests to a GN4 instance (connected to the same DB and Elastic Index) for processing.
+
+
+## Setting up GN5 and GN4
+
+1. Configure GN5 (`application.yml`) so that the `cloud: gateway: mvc:` configuration points to your GN4
+2. Ensure that GN4 is setup to be proxied:
+
+    a) Go the GN4's settings ("Catalog server" section) <br>
+    b) Set this section up so it will create urls that will be correctly routed through GN5 (ie. use GN5's hostname and port)<br>
+    c) Your GN4's path should be the same as the GN5's proxy path.  This will ensure that GN4's session cookies are correctly maintained<br>
+       For example, GN5's proxy at `http://<host>:<port>/geonetwork` and GN4 at `http://<other host>:<other port>/geonetwork`<br>
+       (both at `/geonetwork`)
+
+3. Configure GN4 with JWT Headers Security and add the GN5 `application.yml` `cloud: gateway: mvc:` filter.
+
+    a) [Simple Authentication](auth-json.md) <br>
+    b) [JWT-Based Authentication](auth-jwt.md)
+
+You will manage users in the GN database.
+
+## Using GitHub OIDC Authentication
+
+Typically, you would use the standard username/password authentication thats built into GN5.  However, GitHub authentication is also available.
+
+1. Create a GitHub application (this will give you a `clientId`).  Got to https://github.com/settings/profile then "Developer settings" (left column) then "OAuth Apps" (left column).  See online tutorials on how to create one.
+    * "Authorization callback URL" -  http://localhost:7979/login/oauth2/code/github (use your GN5's host address)
+2. Create a GitHub clientSecret (this will give you a `clientSecret`)
+3. Add the `clientId` and `clientSecret` to GN5's `application.yml` section `security: oauth2: client: registration: github:`
+
+    * fill in the  `clientId:` and `clientSecret:` sections
+
+```yml
+ security:
+    oauth2:
+      client:
+        registration:
+          github:
+            clientId:  ...from your GitHub application...
+            clientSecret: ...from your GitHub application...
+```
+
+Once the user logs into GN5, it will create a user in the database.  The username will either be their email (if they have configured GitHub to have their email address public) or their GitHub username.
+
+Use the tools in the GN Administration -> "Users and Groups" to set the user's permissions.
+   
+
+
 
-1. [Simple Authentication](auth-json.md)
-1. [JWT-Based Authentication](auth-jwt.md)

docs/manual/docs/index.md

@@ -13,5 +13,5 @@ Welcome to GeoNetwork 5.
 
     ---
 
-    Authentication passing between GN5 and GN5 via the proxy gateway.
+    Integrating GN5 and GN4 via the proxy gateway.
 </div>