Reworded the CONTRIBUTING.md doc (#16849)

# Objective

- An attempt at improving the wording surrounding the contributing link
- Fixes #16609

## Solution

- I mostly took Alice's wording and wrote it how I would have said it.
No idea if it's also "clunky", but something's better than nothing

## Testing

- Not relevant

---------

Co-authored-by: Freya Pines <[email protected]>
Co-authored-by: Alice Cecile <[email protected]>

Author: 3 people

CONTRIBUTING.md

@@ -1,3 +1,4 @@
 # Contributing to Bevy
 
-Hey, we've moved our information on contributing to Bevy's website [here](https://bevyengine.org/learn/contribute/introduction). Go give it a read, and thanks for contributing!
+If you'd like to help build Bevy, start by reading this
+[introduction](https://bevyengine.org/learn/contribute/introduction). Thanks for contributing!