Add configfile option to dotnet nuget push (#45050)

Author: martinrrm

docs/core/tools/dotnet-nuget-push.md

@@ -20,6 +20,7 @@ dotnet nuget push [<ROOT>] [-d|--disable-buffering] [--force-english-output]
     [--no-service-endpoint] [-s|--source <SOURCE>] [--skip-duplicate]
     [-sk|--symbol-api-key <API_KEY>] [-ss|--symbol-source <SOURCE>]
     [-t|--timeout <TIMEOUT>]
+    [--configfile <FILE>]
 
 dotnet nuget push -h|--help
 ```
@@ -94,6 +95,10 @@ Alternatively, use the NuGet CLI for the first package, then you can use `dotnet
 
   Specifies the timeout for pushing to a server in seconds. Defaults to 300 seconds (5 minutes). Specifying 0 applies the default value.
 
+- **`--configfile`**
+
+  The NuGet configuration file (*nuget.config*) to use. If specified, only the settings from this file will be used. If not specified, the hierarchy of configuration files from the current directory will be used. For more information, see [Common NuGet Configurations](/nuget/consume-packages/configuring-nuget-behavior).
+
 ## Examples
 
 - Push *foo.nupkg* to the default push source specified in the NuGet config file, using an API key: