🚸 Rewrite the markdown deserializer to improve br… (#1198)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Refactor**
- Updated markdown handling and serialization libraries for improved
performance and accuracy in text formatting.
- **New Features**
- Enhanced rich text and markdown conversion capabilities, providing
users with more reliable and seamless text formatting options.
- **Documentation**
- Added detailed documentation for markdown to rich text conversion and
vice versa, ensuring easier understanding and implementation for
developers.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/lib/markdown/remark-slate/remarkTransformElementChildren.ts

@@ -0,0 +1,17 @@
+import { TDescendant, Value } from '@udecode/plate-common'
+
+import { remarkTransformNode } from './remarkTransformNode'
+import { MdastNode, RemarkPluginOptions } from './types'
+
+export const remarkTransformElementChildren = <V extends Value>(
+  node: MdastNode,
+  lastLineNumber: number,
+  options: RemarkPluginOptions<V>
+): TDescendant[] => {
+  const { children } = node
+  if (!children) return []
+
+  return children.flatMap((child) =>
+    remarkTransformNode(child, lastLineNumber, options)
+  )
+}