Added endpoint and duplicate info

Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/289940

doc/user/packages/nuget_repository/index.md

@@ -106,6 +106,9 @@ You can now add a new source to NuGet with:
 
 #### Project-level endpoint
 
+A project-level endpoint is required to publish NuGet packages to the Package Registry.
+A project-level endpoint is also required to install NuGet packages from a project.
+
 To use the [project-level](#use-the-gitlab-endpoint-for-nuget-packages) NuGet endpoint, add the Package Registry as a source with `nuget`:
 
 ```shell
@@ -122,6 +125,8 @@ nuget source Add -Name "GitLab" -Source "https://gitlab.example.com/api/v4/proje
 
 #### Group-level endpoint
 
+To install a NuGet package from a group, use a group-level endpoint.
+
 To use the [group-level](#use-the-gitlab-endpoint-for-nuget-packages) NuGet endpoint, add the Package Registry as a source with `nuget`:
 
 ```shell
@@ -140,6 +145,9 @@ nuget source Add -Name "GitLab" -Source "https://gitlab.example.com/api/v4/group
 
 #### Project-level endpoint
 
+A project-level endpoint is required to publish NuGet packages to the Package Registry.
+A project-level endpoint is also required to install NuGet packages from a project.
+
 To use the [project-level](#use-the-gitlab-endpoint-for-nuget-packages) NuGet endpoint, add the Package Registry as a source with Visual Studio:
 
 1. Open [Visual Studio](https://visualstudio.microsoft.com/vs/).
@@ -167,6 +175,8 @@ If you get a warning, ensure that the **Location**, **Username**, and
 
 #### Group-level endpoint
 
+To install a package from a group, use a group-level endpoint.
+
 To use the [group-level](#use-the-gitlab-endpoint-for-nuget-packages) NuGet endpoint, add the Package Registry as a source with Visual Studio:
 
 1. Open [Visual Studio](https://visualstudio.microsoft.com/vs/).
@@ -196,6 +206,9 @@ If you get a warning, ensure that the **Location**, **Username**, and
 
 #### Project-level endpoint
 
+A project-level endpoint is required to publish NuGet packages to the Package Registry.
+A project-level endpoint is also required to install NuGet packages from a project.
+
 To use the [project-level](#use-the-gitlab-endpoint-for-nuget-packages) Package Registry as a source for .NET:
 
 1. In the root of your project, create a file named `nuget.config`.
@@ -219,6 +232,8 @@ To use the [project-level](#use-the-gitlab-endpoint-for-nuget-packages) Package
 
 #### Group-level endpoint
 
+To install a package from a group, use a group-level endpoint.
+
 To use the [group-level](#use-the-gitlab-endpoint-for-nuget-packages) Package Registry as a source for .NET:
 
 1. In the root of your project, create a file named `nuget.config`.
@@ -326,8 +341,19 @@ updated:
 
 1. Commit the changes and push it to your GitLab repository to trigger a new CI/CD build.
 
+### Publishing a package with the same name or version
+
+When you publish a package with the same name or version as an existing package,
+the existing package is overwritten.
+
 ## Install packages
 
+To install a NuGet package from the Package Registry, you must first
+[add a project-level or group-level endpoint](#add-the-package-registry-as-a-source-for-nuget-packages).
+
+If multiple packages have the same name and version, when you install
+a package, the most recently-published package is retrieved.
+
 ### Install a package with the NuGet CLI
 
 WARNING: