chore: remove additional incubator references (#12336)

* chore: remove additional incubator references
remove incubator.png from the main docs page

* fix: improve text for contributing-page.mdx

* fix: lint no-unused-vars

docs/src/pages/docs/contributing-page.mdx

@@ -6,9 +6,8 @@ route: /docs/contribution
 
 ## Contributing to Superset
 
-Superset is currently being incubated at
-[the Apache Software Foundation](https://www.apache.org/theapacheway/index.html). The core
-contributors (or committers) to Superset communicate primarily in the following channels (all of
+Superset is an [Apache Software foundation](https://www.apache.org/theapacheway/index.html) project.
+The core contributors (or committers) to Superset communicate primarily in the following channels (all of
 which you can join):
 
 - [Mailing list](https://lists.apache.org/list.html?dev@superset.apache.org)

docs/src/pages/index.tsx

@@ -35,7 +35,6 @@ import GitHubButton from 'react-github-btn';
 
 import { Databases } from '../resources/data';
 import Layout from '../components/layout';
-import Image from '../components/image';
 import DbImage from '../components/DbImage';
 import 'antd/dist/antd.css';
 import SEO from '../components/seo';
@@ -110,10 +109,6 @@ const titleContainer = css`
       width: 400px;
     }
   }
-  .incubator {
-    margin-top: 40px;
-    margin-bottom: 30px;
-  }
   .alert {
     color: #0c5460;
     background-color: #d1ecf1;
@@ -329,9 +324,6 @@ const Theme = () => {
                 </GitHubButton>
               </span>
             </div>
-            <div className="incubator">
-              <Image imageName="incubatorSm" />
-            </div>
             <div>
               <Link to="/docs/intro">
                 <Button type="primary" size="medium">