@clydin @cexbrayat thanks for the feedbacks!

With this commit I added the changes suggested.
Refs #12365

Author: LakhyariMs

packages/angular/cli/commands/doc-impl.ts

@@ -23,7 +23,11 @@ export class DocCommand extends Command<DocCommandSchema> {
     let domain = 'angular.io';
 
     if (options.version) {
-      domain = `v${options.version}.angular.io`;
+      if (options.version == 'next') {
+        domain = 'next.angular.io';
+      } else {
+        domain = `v${options.version}.angular.io`;  
+      }
     }
 
     let searchUrl = `https://${domain}/api?query=${options.keyword}`;

packages/angular/cli/commands/doc.json

@@ -28,7 +28,18 @@
         },
         "version" : {
           "aliases": ["v"],
-          "type": "string",
+          "anyOf": [
+            {
+              "const" : 2
+            },
+            {
+              "type" : "integer",
+              "minimum": 4
+            },
+            {
+              "const": "next"
+            }
+          ],
           "description": "Contains the version of Angular to use for the documentation."
         }
       },