fix(v2): DocSearch should keep working after a new release (#3393)

* We should create an alias for searching last version of docs on DocSearch/Algolia, so that on new version publish, search still works even if new version is not already indexed (https://github.com/facebook/docusaurus/issues/3391)

* commit missing snapshot

* update after algolia changes

* put back facetFilters: [`version:${versions[0]}`] until latest facet is indexed

packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/index.test.ts.snap

@@ -291,6 +291,7 @@ Object {
   "version-current-metadata-prop-751.json": "{
   \\"version\\": \\"current\\",
   \\"label\\": \\"Next\\",
+  \\"isLast\\": true,
   \\"docsSidebars\\": {
     \\"docs\\": [
       {
@@ -615,6 +616,7 @@ Object {
   "version-1-0-0-metadata-prop-608.json": "{
   \\"version\\": \\"1.0.0\\",
   \\"label\\": \\"1.0.0\\",
+  \\"isLast\\": true,
   \\"docsSidebars\\": {
     \\"version-1.0.0/community\\": [
       {
@@ -631,6 +633,7 @@ Object {
   "version-current-metadata-prop-751.json": "{
   \\"version\\": \\"current\\",
   \\"label\\": \\"Next\\",
+  \\"isLast\\": false,
   \\"docsSidebars\\": {
     \\"community\\": [
       {
@@ -1073,6 +1076,7 @@ Object {
   "version-1-0-0-metadata-prop-608.json": "{
   \\"version\\": \\"1.0.0\\",
   \\"label\\": \\"1.0.0\\",
+  \\"isLast\\": false,
   \\"docsSidebars\\": {
     \\"version-1.0.0/docs\\": [
       {
@@ -1115,6 +1119,7 @@ Object {
   "version-1-0-1-metadata-prop-e87.json": "{
   \\"version\\": \\"1.0.1\\",
   \\"label\\": \\"1.0.1\\",
+  \\"isLast\\": true,
   \\"docsSidebars\\": {
     \\"version-1.0.1/docs\\": [
       {
@@ -1151,6 +1156,7 @@ Object {
   "version-current-metadata-prop-751.json": "{
   \\"version\\": \\"current\\",
   \\"label\\": \\"Next\\",
+  \\"isLast\\": false,
   \\"docsSidebars\\": {
     \\"docs\\": [
       {
@@ -1187,6 +1193,7 @@ Object {
   "version-with-slugs-metadata-prop-2bf.json": "{
   \\"version\\": \\"withSlugs\\",
   \\"label\\": \\"withSlugs\\",
+  \\"isLast\\": false,
   \\"docsSidebars\\": {
     \\"version-1.0.1/docs\\": [
       {

packages/docusaurus-plugin-content-docs/src/plugin-content-docs.d.ts

@@ -15,6 +15,7 @@ declare module '@docusaurus/plugin-content-docs-types' {
   export type PropVersionMetadata = {
     version: string;
     label: string;
+    isLast: boolean;
     docsSidebars: PropSidebars;
     permalinkToSidebar: PermalinkToSidebar;
   };

packages/docusaurus-plugin-content-docs/src/props.ts

@@ -67,6 +67,7 @@ export function toVersionMetadataProp(
   return {
     version: loadedVersion.versionName,
     label: loadedVersion.versionLabel,
+    isLast: loadedVersion.isLast,
     docsSidebars: toSidebarsProp(loadedVersion),
     permalinkToSidebar: loadedVersion.permalinkToSidebar,
   };