Update cheatsheets

dotnet-add-reference

@@ -0,0 +1,17 @@
+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# dotnet add reference
+
+> Add .NET project-to-project references.
+> More information: <https://learn.microsoft.com/dotnet/core/tools/dotnet-add-reference>.
+
+- Add a reference to the project in the current directory:
+
+`dotnet add reference {{path/to/reference.csproj}}`
+
+- Add a reference to the specific project:
+
+`dotnet add {{path/to/project.csproj}} reference {{path/to/reference.csproj}}`