Merge #459

459: add old code compat to the readme r=haxscramper a=haxscramper

This part had already been present in the readme for some time. 

Original version was

```
<details>
<summary class="blue">Will this break my Nim code?</summary>
</br>
Maybe. Many experienced users will know that a lot of current code 'works' because of various hacks, or create hacks themselves to make code work. See <a href="https://github.com/nim-works/nimskull/issues/8">#8</a> and the <a href="https://github.com/nim-works/nimskull#direction">direction</a> for more on this.
</details>
```  

I rephrased new to an extended, "maybe, but we won't have any guarantees on that matter"

Co-authored-by: haxscramper <haxscramper@gmail.com>

Author: bors[bot]

readme.md

@@ -228,6 +228,12 @@ existing contributors are already familiar with the current code base. We chose
 to evolve it.
 </details>
 
+<details>
+<summary class="blue">Will this break my Nim code?</summary>
+</br>
+This project aims to become a different programming language, so do not expect source code compatibility. If you want Nim then use it.
+</details>
+
 <details>
 <summary class="blue">What's the rationale for this fork?</summary>
 </br>