### Summary
Corrected a grammar typo in the Turkish translation file `README.tr.md`.
- "Açık Kaynakın" → "Açık Kaynağın"
This fix improves the grammatical accuracy and clarity of the documentation for Turkish-speaking contributors.
- [x] I had fun going through this tutorial (ノ^o^)ノ and learned on the way ٩(^◡^)۶
- [ ] There are some things I'd like to improve in this tutorial. I have written them below.
- [ ] There were steps where I had errors while following this tutorial. I have written them below.