fix(v2): custom searchbar should appear even if themeconfig.algolia is undefined (#1909)

* fix(v2): custom searchbar should appear even if themeconfig.algolia is undefined

* nits

* Docs docs

* inaccuracy

* changelog

* nits

website/docs/theme-classic.md

@@ -0,0 +1,51 @@
+---
+id: theme-classic
+title: Classic Theme Configuration
+---
+
+_This section is a work in progress._
+
+## Navbar
+
+### Navbar Title & Logo
+
+You can add a logo and title to the navbar via `themeConfig.navbar`. Logo can be placed in [static folder](static-assets.md).
+
+```js
+// docusaurus.config.js
+module.exports = {
+  themeConfig: {
+    navbar: {
+      title: 'Site Title',
+      logo: {
+        alt: 'Site Logo',
+        src: 'img/logo.svg',
+      },
+    }
+}
+```
+
+### Navbar Links
+
+You can add links to the navbar via `themeConfig.navbar.links`:
+
+```js
+// docusaurus/config.js
+module.exports = {
+  themeConfig: {
+    navbar: {
+      links: [
+        {
+          to: 'docs/docusaurus.config.js',
+          label: 'docusaurus.config.js',
+          position: 'left',
+        },
+        // ... other links
+      ],
+    }
+}
+```
+
+Outbound links automatically get `target="_blank" rel="noopener noreferrer"`.
+
+## Footer