CLI usage instructions

Plus added  a PyPI badge

README.md

@@ -1,5 +1,7 @@
 # MarkItDown
 
+[![PyPI](https://img.shields.io/pypi/v/markitdown.svg)](https://pypi.org/project/markitdown/)
+
 The MarkItDown library is a utility tool for converting various files to Markdown (e.g., for indexing, text analysis, etc.)
 
 It presently supports:
@@ -23,6 +25,16 @@ result = markitdown.convert("test.xlsx")
 print(result.text_content)
 ```
 
+To use this as a command-line utility, install it and then run it like this:
+
+```bash
+markitdown path-to-file.pdf
+```
+This will output Markdown to standard output. You can save it like this:
+```bash
+markitdown path-to-file.pdf > document.md
+```
+
 ## Contributing
 
 This project welcomes contributions and suggestions.  Most contributions require you to agree to a