text-splitter[minor]: Declare MarkdownHeaderTextSplitter deprecated. Use MarkdownTextSplitter.

[pprados]

Langchain offers two Markdown splitter implementations:

• MarkdownTextSplitter
• MarkdownHeaderTextSplitter

The MarkdownHeaderTextSplitter class is not langchain compliant, since it inherits from anyone. It is not possible to use in a function or class that expects a TextSplitter.

In my experience, users who come across this class don't know that there is another exists. If they need to be TextSplitter compatible, they write a new class.

We propose to declare it deprecated, and referencing MarkdownTextSplitter.