Add PgAdmin in postgresql integration (#1603)

* Add PgAdmin in postgresql integration

Add simple document for PgAdmin section in postgresql integration

* Add PgAdmin in postgresql-ef integration

docs/database/includes/postgresql-pgadmin.md

@@ -0,0 +1,11 @@
+When adding PostgreSQL resources to the `builder` with the `AddPostgres` method, you can chain calls to `WithPgAdmin` to add the [**dpage/pgadmin4**](https://www.pgadmin.org/) container. This container is a cross-platform client for PostgreSQL databases, that serves a web-based admin dashboard. Consider the following example:
+
+```csharp
+var postgres = builder.AddPostgres("postgres")
+                      .WithPgAdmin();
+
+var postgresdb = postgres.AddDatabase("postgresdb");
+
+var exampleProject = builder.AddProject<Projects.ExampleProject>()
+                            .WithReference(postgresdb);
+```

docs/database/postgresql-entity-framework-integration.md

@@ -78,6 +78,8 @@ var myService = builder.AddProject<Projects.MyService>()
 
 [!INCLUDE [postgresql-pgweb](includes/postgresql-pgweb.md)]
 
+[!INCLUDE [postgresql-pgadmin](includes/postgresql-pgadmin.md)]
+
 [!INCLUDE [postgresql-flexible-server](includes/postgresql-flexible-server.md)]
 
 ## Configuration

docs/database/postgresql-integration.md

@@ -64,6 +64,8 @@ var exampleProject = builder.AddProject<Projects.ExampleProject>()
 
 [!INCLUDE [postgresql-pgweb](includes/postgresql-pgweb.md)]
 
+[!INCLUDE [postgresql-pgadmin](includes/postgresql-pgadmin.md)]
+
 [!INCLUDE [postgresql-flexible-server](includes/postgresql-flexible-server.md)]
 
 ## Configuration