format: homogenize c# category title

right markdown escape instead of use HTML entities

casts/free-podcasts-screencasts-en.md

@@ -40,7 +40,7 @@
 * [The complete Android Application Development Course - Work Great in 2020](https://www.youtube.com/playlist?list=PLknSwrodgQ72X4sKpzf5vT8kY80HKcUSe) - Android Developer (screencast)
 
 
-### <a id="csharp"></a>C&#x23;
+### <a id="csharp"></a>C\#
 
 * [Beginning C# with Unity](https://www.youtube.com/playlist?list=PLFgjYYTq6xyhtVK6VzLiFe3pmBu-XSNlX) - Brian Douglas Moakley, VegetarianZombie (screencast)
 * [How to program in C# - Beginner Course \| Brackeys](https://www.youtube.com/playlist?list=PLPV2KyIb3jR6ZkG8gZwJYSjnXxmfPAl51) - Asbjørn Thirslund (screencast)