feat(readme) add creation/contribution notes

README.md

@@ -9,7 +9,13 @@ Getting help:
 
 - Join the [5etools Discord Server](https://discord.gg/v3AXzcW) and ask in the #homebrew channel.
 
+Creating and Contributing:
+
+- The easiest way to make your own, is to copy one of the existing 'brews as a template and/or parts of the main [5etools classes data](https://static.5etools.com/data/classes.json).
+- Contributions are welcome. For the Git-literate, make a pull request. For everyone else, create an Issue and post a link to your file (PasteBin is fine), and I (or other maintainers, in future) can add it for you.
+
 Useful links:
 
  - https://5etools.com/demo.html (a demo of the renderer and JSON format)
  - https://jsonlint.com/ (error-check your JSON)
+ - https://www.sublimetext.com/ (top-notch text editor)