docs: Add sample on how to distribute SQL files from a NuGet package

[MrDave1999]

Resolves #107

The package was published here: https://www.nuget.org/packages/YeSql.Net.Example.QueryReuse

[MrDave1999]

These instructions to MSBuild do the magic:

  <ItemGroup>
    <Content Include="**\*.sql">
      <Pack>true</Pack>
      <PackagePath>contentFiles\any\$(TargetFramework)\yesql\</PackagePath>
      <PackageCopyToOutput>true</PackageCopyToOutput>
    </Content>
  </ItemGroup>

• Pack property tells MSBuild to include the content (SQL files) to the nuget package.
• PackagePath property is to specify the path where the SQL files will be copied to the nuget package.
  SQL files must be copied to this path: contentFiles\any\$(TargetFramework). $(TargetFramework) macro is expanded in this case to "netstandard2.0".
  See documentation: https://learn.microsoft.com/en-us/nuget/reference/msbuild-targets#including-content-in-a-package
• PackageCopyToOutput property will tell MSBuild to copy the SQL files to the output directory of the project that references the nuget package.

When the package is created with the "dotnet pack" command, the .nuspec file must contain the following:

<contentFiles>
   <files include="any/netstandard2.0/yesql/Receipts/receipt.sql" buildAction="Content" copyToOutput="true" />
   <files include="any/netstandard2.0/yesql/Receipts/receiptDetails.sql" buildAction="Content" copyToOutput="true"  />
</contentFiles>

Obviously this is just an example but the .nuspec file should contain the files that should be copied to the output directory of the project that references the nuget package.