False Positive: text.md suggested to be text.MD

**What got flagged?**
It reports the conical spelling of "md" in harper is "MD".

**Why is this incorrect?**
It suggests the change even when md is a file extension. I understand that paths in markdown are generally inside \``, but not always, and filenames should always be lowercase.

**Example of correct usage:**
I made the install.md file like you asked.

Edit:

I'm now noticing that this applies to more than just md. For example with .zip. I think there should be a list of file extensions that get special treatment.

Start by reproducing the reported suggestions with install.md and .zip examples, then locate the spelling rule that treats file extensions as words and proposes uppercase forms. Done means lowercase filename extensions such as md and zip are not incorrectly flagged, while the issue's ordinary spelling behavior remains covered by tests.

Written by the indexing model from the issue text.