Basic C# script for Unity, replaces the default script. Calls in more Unity packages by default so you don't have to remember too and instead can focus on coding; and is organized a little better in my opinion.
The '.txt' extension is correct, please leave that as is. And the 01 at the front is so unity knows what priority order it has when picking a script template, you don't need to replace your existing templates and in-fact I'd recommend keeping those, just in-case.
File path for Unity:
Windows
C:\Program Files\Unity\Hub\Editor\YOUR UNITY VERSION\Editor\Data\Resources\ScriptTemplates
Mac
/Applications/Unity/Editor/Data/Resources/ScriptTemplates
Enjoy :)
