doc: fix LIBRARY_PATH comment

Now that we build capnp, qt isn't the only native package.

Author: fanquake

contrib/guix/libexec/build.sh

@@ -74,7 +74,7 @@ build_CC="${NATIVE_GCC}/bin/gcc -isystem ${NATIVE_GCC}/include"
 build_CXX="${NATIVE_GCC}/bin/g++ -isystem ${NATIVE_GCC}/include/c++ -isystem ${NATIVE_GCC}/include"
 
 case "$HOST" in
-    *darwin*) export LIBRARY_PATH="${NATIVE_GCC}/lib" ;; # Required for qt/qmake
+    *darwin*) export LIBRARY_PATH="${NATIVE_GCC}/lib" ;; # Required for native packages
     *mingw*) export LIBRARY_PATH="${NATIVE_GCC}/lib" ;;
     *)
         NATIVE_GCC_STATIC="$(store_path gcc-toolchain static)"