Fixed issue #17397 by updating the markdown format in MarkdownReader

[Riddhimaan-Senapati]

Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

I updated the markdown regex format in MarkdownReader in llama_index.readers.file as suggested in the below issue.

Fixes #17397

New Package?

Did I fill in the tool.llamahub section in the pyproject.toml and provide a detailed README.md for my new integration or package?

• Yes
• No

Version Bump?

Did I bump the version in the pyproject.toml file of the package I am updating? (Except for the llama-index-core package)

• Yes
• No

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Your pull-request will likely not be merged unless it is covered by some form of impactful unit testing.

• I added new unit tests to cover this change
• I believe this change is already covered by existing unit tests

Suggested Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added Google Colab support for the newly added notebooks.
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I ran make format; make lint to appease the lint gods

[Riddhimaan-Senapati]

@logan-markewich Can you review this PR, it fixes issue #17397 by updating the markdown regex format

[minglu7]

The new regular expression is correct, and I'm curious why no one noticed this for so long.

[minglu7]

i think following method could be better, because somethimes the name of image makes sense:
def remove_images(self, content: str) -> str:
"""Remove images in markdown content but keep the description."""
pattern = r""
return re.sub(pattern, r"\1", content)

[Riddhimaan-Senapati]

Done. updated the function. These things happen sometimes.