Add README.md to the NuGet package

Author: Tarmil

src/Diffract/paket.template

@@ -1,4 +1,4 @@
-type project
+type project
 licenseExpression MIT
 licenseUrl https://licenses.nuget.org/MIT
 authors Loïc Denuzière
@@ -10,4 +10,7 @@ repositoryUrl https://github.com/d-edge/Diffract
 repositoryType git
 requireLicenseAcceptance true
 tags Dedge;Diffract;Diff;Equals;Test;Comparison
-iconUrl https://raw.githubusercontent.com/d-edge/Diffract/main/diffract-64x64.png
+iconUrl https://raw.githubusercontent.com/d-edge/Diffract/main/diffract-64x64.png
+readme README.md
+files
+    ../../README.md ==> .