aaphoto: drop unnecessary `rec` and inline pname in doc path

- `rec` is not needed since no self-references remain in the derivation.
- Use literal `aaphoto` in `$out/share/doc` instead of `${pname}` for clarity
and to avoid unnecessary indirection.

pkgs/by-name/aa/aaphoto/package.nix

···
   llvmPackages,
 }:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation {
   pname = "aaphoto";
   version = "0.45";
 
···
   ];
 
   postInstall = ''
-    install -Dm644 NEWS README REMARKS TODO -t $out/share/doc/${pname}
+    install -Dm644 NEWS README REMARKS TODO -t $out/share/doc/aaphoto
   '';
 
   meta = {