documentation: mention we can't use the distro toolchain as external

    </ul>

    <p>We also do not support using the distribution toolchain (i.e

    the gcc/binutils/C library installed by your distribution) as the

    toolchain to build software for the target. This is because your

    distribution toolchain is not a "pure" toolchain (i.e only with

    the C/C++ library), so we cannot import it properly into the

    Buildroot build environment. So even if you are building a system

    for a x86 or x86_64 target, you have to generate a

    cross-compilation toolchain with Buildroot or Crosstool-NG.</p>

    <h2 id="add_packages">Adding new packages to Buildroot</h2>

    <p>This section covers how new packages (userspace libraries or