feat(docs): migrate bs docs

blocksuite/docs-site/guide/store.md

@@ -0,0 +1,62 @@
+# `@blocksuite/store`
+
+This package is the data layer for modeling collaborative document states. It's natively built on the CRDT library [Yjs](https://github.com/yjs/yjs), powering all BlockSuite documents with built-in real-time collaboration and time-travel capabilities.
+
+## `Doc`
+
+In BlockSuite, a [`Doc`](/api/@blocksuite/store/classes/Doc.html) is the container for a block tree, providing essential functionalities for creating, retrieving, updating, and deleting blocks inside it. Under the hood, every doc holds a Yjs [subdocument](https://docs.yjs.dev/api/subdocuments).
+
+Besides the block tree, the [selection](./selection) state is also stored in the [`doc.awarenessStore`](/api/@blocksuite/store/classes/Doc.html#awarenessstore) inside the doc. This store is also built on top of the Yjs [awareness](https://docs.yjs.dev/api/about-awareness).
+
+## `DocCollection`
+
+In BlockSuite, a [`DocCollection`](/api/@blocksuite/store/classes/DocCollection.html) is defined as an opt-in collection of multiple docs, providing comprehensive features for managing cross-doc updates and data synchronization. You can access the collection via the `doc.collection` getter, or you can also create a collection manually:
+
+```ts
+import { DocCollection, Schema } from '@blocksuite/store';
+
+const schema = new Schema();
+
+// You can register a batch of block schemas to the collection
+schema.register(AffineSchemas);
+
+const collection = new DocCollection({ schema });
+collection.meta.initialize();
+```
+
+Then multiple `doc`s can be created under the collection:
+
+```ts
+const collection = new DocCollection({ schema });
+collection.meta.initialize();
+
+// This is an empty doc at this moment
+const doc = collection.createDoc();
+```
+
+As an example, the `createEmptyDoc` is a simple helper implemented exactly in this way ([source](https://github.com/toeverything/blocksuite/blob/master/packages/presets/src/helpers/index.ts)):
+
+```ts
+import { AffineSchemas } from '@blocksuite/blocks/models';
+import { Schema, DocCollection } from '@blocksuite/store';
+
+export function createEmptyDoc() {
+  const schema = new Schema().register(AffineSchemas);
+  const collection = new DocCollection({ schema });
+  collection.meta.initialize();
+  const doc = collection.createDoc();
+
+  return {
+    doc,
+    async init() {
+      await doc.load(() => {
+        const rootBlockId = doc.addBlock('affine:page', {});
+        doc.addBlock('affine:surface', {}, rootBlockId);
+        const noteId = doc.addBlock('affine:note', {}, rootBlockId);
+        doc.addBlock('affine:paragraph', {}, noteId);
+      });
+      return doc;
+    },
+  };
+}
+```