fixup! Document cross compilers in INSTALL.adoc

INSTALL.adoc

@@ -224,19 +224,13 @@ make installcross
 Notes:
 
 * It is advisable to choose a `prefix` that will not end up in installing the
-  cross compiler in your `$PATH`, since you probably want to make sure the
-  `ocamlopt` command runs the non-cross compiler, not the cross one. When you
-  want to call the cross compiler, you will just call it using its full path or
-  add it temporarily to your `$PATH`.
+  cross compiler in your `$PATH`, since you probably want an unqualified
+  `ocamlopt` invocation to call the non-cross compiler, not the cross one. To
+  call the cross compiler, you will just use its full path or add it temporarily
+  to your `$PATH`.
 * The cross compiler to Windows needs `flexdll` to link the binaries. A simple
   way to get it is to use the `flexdll` submodule (`git submodule update --init`
   if needed) and let the `crossopt` target bootstrap `flexdll`.
-* TODO If `pkg-config --libs libzstd` doesn't return the flags used to link the
-  non-cross runtime, you can specify them with:
-+
-....
-make crossopt -j HOST_ZSTD_FLAGS="..."
-....
 
 === Using the cross compiler