Remove duplicate line from compiling_with_mono.rst

Removed like 15 because NuGet was already stated at line 13.

development/compiling/compiling_with_mono.rst

@@ -12,7 +12,6 @@ Requirements
 - MSBuild
 - NuGet
 - pkg-config
-- NuGet
 
 You may need to import necessary certificates for NuGet to perform HTTPS requests. You can do this
 with the following command (on Windows, you can run it from the Mono command line prompt):