Restore valid Netflix and TutsPlus links that were incorrectly removed

Co-authored-by: mmcky <[email protected]>

Author: Copilot

lectures/about_py.md

@@ -117,6 +117,7 @@ It is used and supported extensively by large tech firms including
 
 * [Google](https://www.google.com/)
 * [OpenAI](https://openai.com/)
+* [Netflix](https://www.netflix.com/)
 * [Meta](https://opensource.fb.com/)
 * [Amazon](https://www.amazon.com/)
 * [Reddit](https://www.reddit.com/)

lectures/writing_good_code.md

@@ -189,6 +189,8 @@ But as a programmer, your aim should be to **automate** repetition, **not** do i
 
 More importantly, repeating the same logic in different places means that eventually one of them will likely be wrong.
 
+If you want to know more, read the excellent summary found on [this page](https://code.tutsplus.com/tutorials/3-key-software-principles-you-must-understand--net-25161).
+
 We'll talk about how to avoid repetition below.
 
 ### Minimize Global Variables