Readme.rst: List submodules and links to licenses

Update list of content that is covered by a license other than
the BSD-2-Clause Plus Patent License and break out list of
content that is included as a git submodule from upstream
projects.

* Use alphabetic order of content
* Remove references to IntelFrameworkModulePkg
* Add reference for UnitTestFrameworkPkg use of cmocka

Cc: Andrew Fish <afish@apple.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>