Update package properties. Include package README.

Author: sharpjs

Directory.Build.props

@@ -19,7 +19,9 @@
     <Authors>Jeffrey Sharp</Authors>
     <Company>Subatomix Research Inc.</Company>
     <Copyright>© $([System.DateTime]::UtcNow.Year) $(Company)</Copyright>
-    <PackageLicenseExpression>ISC</PackageLicenseExpression>
+    <PackageLicenseExpression>MIT</PackageLicenseExpression>
+    <PackageLicenseFile>LICENSE.txt</PackageLicenseFile>
+    <PackageReadmeFile>README.md</PackageReadmeFile>
     <PackageProjectUrl>https://github.com/sharpjs/Prequel</PackageProjectUrl>
     <PackageTags>sqlcmd sql preprocessor</PackageTags>
     <PackageReleaseNotes>$(PackageProjectUrl)/blob/main/CHANGES.md</PackageReleaseNotes>

Directory.Build.targets

@@ -12,10 +12,12 @@
   -->
 
   <ItemGroup Condition="'$(IsPackable)' == 'true'">
-    <None Include="..\icon.png" Link="Properties\icon.png"
-          Pack="true" PackagePath="" CopyToOutputDirectory="Never" />
-    <None Include="..\LICENSE.txt" Link="Properties\LICENSE.txt"
+    <None Include="..\icon.png" LinkBase="Properties"
+          Pack="true" PackagePath="$(PackageIcon)" CopyToOutputDirectory="Never" />
+    <None Include="..\LICENSE.txt" LinkBase="Properties"
           Pack="true" PackagePath="$(PackageLicenseFile)" CopyToOutputDirectory="Never" />
+    <None Include="..\README.md" LinkBase="Properties"
+          Pack="true" PackagePath="$(PackageReadmeFile)" CopyToOutputDirectory="Never" />
   </ItemGroup>
 
   <!-- Visibility -->