Clean up and document project files (#4560)

tools/generate_natvis/README.md

@@ -1,10 +1,9 @@
-generate_natvis.py
-==================
+# generate_natvis.py
 
 Generate the Natvis debugger visualization file for all supported namespace combinations.
 
 ## Usage
 
-```
+```shell
 ./generate_natvis.py --version X.Y.Z output_directory/
 ```

tools/generate_natvis/requirements.txt

@@ -0,0 +1 @@
+jinja2==3.1.5