text: Title: Fix capitalisation of Markdown (prefer markdown) as per Vale suggestion
  Body: Vale recommends that the word Markdown is not capitalised except at the start of a sentence.
  
  <img width="549" alt="image" src="https://github.com/user-attachments/assets/a2edcb7f-74c6-4622-b833-3bca9c4b51dd">
  
  
  Task: Search across Vizro docs (vizro-core and vizro-ai) for instances of `Markdown` and replace with discretion.
  
  ```markdown
  <!-- vale off -->
  Legitimate use of "Markdown" rather than "markdown" (within a sentence, since Vale won't flag sentence case as an issue)
  <!--vale on-->
  ```