Adding alternative NuGet package source in Visual Studio solution

While it's possible to add a new package source to Visual Studio this is not optimal if there are more than one developer or if a build server is used.

An alternative is to add a .nuget folder and within that folder add a NuGet.config file with the following content:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
   <packageSources>
      <add key="NuGet official package source" value="https://nuget.org/api/v2/" />
      <add key="Some other package source" value="some url to the other package source" />
   </packageSources>
   <disabledPackageSources />
   <activePackageSource>
      <!-- this tells that all of them are active -->
      <add key="All" value="(Aggregate source)" />
   </activePackageSource>
</configuration>

Source
https://docs.nuget.org/consume/nuget-config-file