docs(plugin-search): add info on collection reindexing (#9764)

Adds documentation for the feature introduced with [plugin-search
collection reindexing](https://github.com/payloadcms/payload/pull/9391).
This also fixes an invalid scss import in one of the examples.

Credit to @rilrom for the invalid css import find!

docs/admin/components.mdx

@@ -445,7 +445,7 @@ Then to colorize your Custom Component's background, for example, you can use th
 Payload also exports its [SCSS](https://sass-lang.com) library for reuse which includes mixins, etc. To use this, simply import it as follows into your `.scss` file:
 
 ```scss
-@import '~payload/scss';
+@import '~@payloadcms/ui/scss';
 
 .my-component {
   @include mid-break {

docs/plugins/search.mdx

@@ -33,6 +33,7 @@ This plugin is a great way to implement a fast, immersive search experience such
 - Allows you to query search results using first-party Payload APIs
 - Allows you to query documents without triggering any of their underlying hooks
 - Allows you to easily prioritize search results by collection or document
+- Allows you to reindex search results by collection on demand
 
 ## Installation
 
@@ -81,7 +82,7 @@ export default config
 
 The `collections` property is an array of collection slugs to enable syncing to search. Enabled collections receive a `beforeChange` and `afterDelete` hook that creates, updates, and deletes its respective search record as it changes over time.
 
-### `localize`
+#### `localize`
 
 By default, the search plugin will add `localization: true` to the `title` field of the newly added `search` collection if you have localization enabled. If you would like to disable this behavior, you can set this to `false`.
 
@@ -159,6 +160,14 @@ When `syncDrafts` is true, draft documents will be synced to search. This is fal
 
 If true, will delete documents from search whose status changes to draft. This is true by default. You must have [Payload Drafts](https://payloadcms.com/docs/versions/drafts) enabled for this to apply.
 
+#### `reindexBatchSize`
+
+A number that, when specified, will be used as the value to determine how many search documents to fetch for reindexing at a time in each batch. If not set, this will default to `50`.
+
+### Collection reindexing
+
+Collection reindexing allows you to recreate search documents from your search-enabled collections on demand. This is useful if you have existing documents that don't already have search indexes, commonly when adding `plugin-search` to an existing project. To get started, navigate to your search collection and click the pill in the top right actions slot of the list view labelled `Reindex`. This will open a popup with options to select one of your search-enabled collections, or all, for reindexing.
+
 ## TypeScript
 
 All types can be directly imported: