Added docker support

Dockerfile

@@ -0,0 +1,18 @@
+FROM mcr.microsoft.com/dotnet/nightly/sdk:6.0 AS build-env
+WORKDIR /app
+
+COPY *.sln ./
+COPY PhonebookService.Api/*.csproj PhonebookService.Api/
+COPY PhonebookService.Domain/*.csproj PhonebookService.Domain/
+COPY PhonebookService.Infrastructure/*.csproj PhonebookService.Infrastructure/
+RUN dotnet restore
+
+COPY . ./
+RUN dotnet publish -c Release -o out
+
+FROM mcr.microsoft.com/dotnet/aspnet:6.0
+WORKDIR /app
+COPY --from=build-env /app/out .
+EXPOSE 80
+ENTRYPOINT [ "dotnet", "PhonebookService.Api.dll" ]
+