affine: copy license to docs

Moving just to $out can result in collisions.
Best practise is to move the license files to the docs directory.

See:
https://discourse.nixos.org/t/collision-between-2-license-txt-from-2-different-packages/22071

pkgs/by-name/af/affine/package.nix

@@ -29,7 +29,8 @@ in {
   postInstall = ''
     mkdir -p $out/lib
     cp -r ./resources/* -t $out/lib/
-    cp LICENSE* $out/
+    mkdir -p $out/share/doc/affine/
+    cp LICENSE* $out/share/doc/affine/
     install -Dm644 ${icon} $out/share/pixmaps/affine.png
     makeWrapper "${electron}/bin/electron" $out/bin/affine \
       --inherit-argv0 \