docs: add algolia crawler config (closes #2592)

docs/reference/default-theme-search.md

@@ -78,13 +78,17 @@ export default defineConfig({
           /**
            * @type {Pick<import('minisearch').Options, 'extractField' | 'tokenize' | 'processTerm'>}
            */
-          options: { /* ... */ },
+          options: {
+            /* ... */
+          },
           /**
            * @type {import('minisearch').SearchOptions}
            * @default
            * { fuzzy: 0.2, prefix: true, boost: { title: 4, text: 2, titles: 1 } }
            */
-          searchOptions: { /* ... */ }
+          searchOptions: {
+            /* ... */
+          }
         }
       }
     }
@@ -181,6 +185,114 @@ export default defineConfig({
 
 [These options](https://github.com/vuejs/vitepress/blob/main/types/docsearch.d.ts) can be overridden. Refer official Algolia docs to learn more about them.
 
+### Crawler Config
+
+Here is an example config based on what this site uses:
+
+```ts
+new Crawler({
+  appId: '...',
+  apiKey: '...',
+  rateLimit: 8,
+  startUrls: ['https://vitepress.dev/'],
+  renderJavaScript: false,
+  sitemaps: [],
+  exclusionPatterns: [],
+  ignoreCanonicalTo: false,
+  discoveryPatterns: ['https://vitepress.dev/**'],
+  schedule: 'at 05:10 on Saturday',
+  actions: [
+    {
+      indexName: 'vitepress',
+      pathsToMatch: ['https://vitepress.dev/**'],
+      recordExtractor: ({ $, helpers }) => {
+        return helpers.docsearch({
+          recordProps: {
+            lvl1: '.content h1',
+            content: '.content p, .content li',
+            lvl0: {
+              selectors: '',
+              defaultValue: 'Documentation'
+            },
+            lvl2: '.content h2',
+            lvl3: '.content h3',
+            lvl4: '.content h4',
+            lvl5: '.content h5'
+          },
+          indexHeadings: true
+        })
+      }
+    }
+  ],
+  initialIndexSettings: {
+    vitepress: {
+      attributesForFaceting: ['type', 'lang'],
+      attributesToRetrieve: ['hierarchy', 'content', 'anchor', 'url'],
+      attributesToHighlight: ['hierarchy', 'hierarchy_camel', 'content'],
+      attributesToSnippet: ['content:10'],
+      camelCaseAttributes: ['hierarchy', 'hierarchy_radio', 'content'],
+      searchableAttributes: [
+        'unordered(hierarchy_radio_camel.lvl0)',
+        'unordered(hierarchy_radio.lvl0)',
+        'unordered(hierarchy_radio_camel.lvl1)',
+        'unordered(hierarchy_radio.lvl1)',
+        'unordered(hierarchy_radio_camel.lvl2)',
+        'unordered(hierarchy_radio.lvl2)',
+        'unordered(hierarchy_radio_camel.lvl3)',
+        'unordered(hierarchy_radio.lvl3)',
+        'unordered(hierarchy_radio_camel.lvl4)',
+        'unordered(hierarchy_radio.lvl4)',
+        'unordered(hierarchy_radio_camel.lvl5)',
+        'unordered(hierarchy_radio.lvl5)',
+        'unordered(hierarchy_radio_camel.lvl6)',
+        'unordered(hierarchy_radio.lvl6)',
+        'unordered(hierarchy_camel.lvl0)',
+        'unordered(hierarchy.lvl0)',
+        'unordered(hierarchy_camel.lvl1)',
+        'unordered(hierarchy.lvl1)',
+        'unordered(hierarchy_camel.lvl2)',
+        'unordered(hierarchy.lvl2)',
+        'unordered(hierarchy_camel.lvl3)',
+        'unordered(hierarchy.lvl3)',
+        'unordered(hierarchy_camel.lvl4)',
+        'unordered(hierarchy.lvl4)',
+        'unordered(hierarchy_camel.lvl5)',
+        'unordered(hierarchy.lvl5)',
+        'unordered(hierarchy_camel.lvl6)',
+        'unordered(hierarchy.lvl6)',
+        'content'
+      ],
+      distinct: true,
+      attributeForDistinct: 'url',
+      customRanking: [
+        'desc(weight.pageRank)',
+        'desc(weight.level)',
+        'asc(weight.position)'
+      ],
+      ranking: [
+        'words',
+        'filters',
+        'typo',
+        'attribute',
+        'proximity',
+        'exact',
+        'custom'
+      ],
+      highlightPreTag: '<span class="algolia-docsearch-suggestion--highlight">',
+      highlightPostTag: '</span>',
+      minWordSizefor1Typo: 3,
+      minWordSizefor2Typos: 7,
+      allowTyposOnNumericTokens: false,
+      minProximity: 1,
+      ignorePlurals: true,
+      advancedSyntax: true,
+      attributeCriteriaComputedByMinProximity: true,
+      removeWordsIfNoResults: 'allOptional'
+    }
+  }
+})
+```
+
 <style>
 img[src="/search.png"] {
   width: 100%;