docs: improvement to sidebar (#11810)

* docs: improvement to sidebar

* fix sidebar

www/apps/book/generated/sidebar.mjs

@@ -1148,18 +1148,17 @@ export const generatedSidebars = [
             "type": "link",
             "path": "/learn/build",
             "title": "Build",
-            "chapterTitle": "8. Production",
+            "children": [],
+            "chapterTitle": "8.1. Build",
+            "number": "8.1."
+          },
+          {
+            "loaded": true,
+            "isPathHref": true,
+            "type": "link",
+            "path": "/learn/deployment",
+            "title": "Deployment Overview",
             "children": [
-              {
-                "loaded": true,
-                "isPathHref": true,
-                "type": "link",
-                "path": "/learn/deployment",
-                "title": "Deployment Overview",
-                "children": [],
-                "chapterTitle": "8.1. Deployment Overview",
-                "number": "8.1."
-              },
               {
                 "loaded": true,
                 "isPathHref": true,
@@ -1167,13 +1166,16 @@ export const generatedSidebars = [
                 "path": "/learn/deployment/general",
                 "title": "General Deployment",
                 "children": [],
-                "chapterTitle": "8.2. General Deployment",
-                "number": "8.2."
+                "chapterTitle": "8.2.1. General Deployment",
+                "number": "8.2.1."
               }
             ],
-            "number": "8."
+            "chapterTitle": "8.2. Deployment Overview",
+            "number": "8.2."
           }
-        ]
+        ],
+        "chapterTitle": "8. Production",
+        "number": "8."
       },
       {
         "loaded": true,

www/apps/book/sidebar.mjs

@@ -597,20 +597,25 @@ export const sidebars = [
         ],
       },
       {
-        type: "link",
-        path: "/learn/build",
-        title: "Build",
-        chapterTitle: "Production",
+        type: "category",
+        title: "Production",
         children: [
+          {
+            type: "link",
+            path: "/learn/build",
+            title: "Build",
+          },
           {
             type: "link",
             path: "/learn/deployment",
             title: "Deployment Overview",
-          },
-          {
-            type: "link",
-            path: "/learn/deployment/general",
-            title: "General Deployment",
+            children: [
+              {
+                type: "link",
+                path: "/learn/deployment/general",
+                title: "General Deployment",
+              },
+            ],
           },
         ],
       },

www/packages/docs-ui/src/providers/Sidebar/index.tsx

@@ -301,7 +301,7 @@ export const SidebarProvider = ({
   }, [scrollableElement, isBrowser])
 
   const activeMainSidebar = useMemo(() => {
-    if (!activePath) {
+    if (!activePath || sidebars.length === 1) {
       // set first sidebar as active
       return sidebars[0]
     }
@@ -357,7 +357,7 @@ export const SidebarProvider = ({
 
   const shownSidebar = useMemo(() => {
     if (!sidebarHistory.length) {
-      return
+      return sidebars.length === 1 ? sidebars[0] : undefined
     }
 
     return getSidebar(sidebarHistory[sidebarHistory.length - 1])