ReadMe.rst: Add Apache License 2.0 and update submodule list

- Adds Apache License 2.0 as an acceptable source license per
  discussion in https://edk2.groups.io/g/devel/message/110226
- Updates the URL for existing licenses to match the current path
  used by opensource.org.
- The submodule list in this file is stale and is very prone to
  being forgotten. The list of submodules in the submodules setion
  is replaced with a link to .gitmodules which has an active list
  of submodules at any given time.

Cc: Andrew Fish <afish@apple.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Cc: Sean Brogan <sean.brogan@microsoft.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Acked-by: Pedro Falcato <pedro.falcato@gmail.com>
1 file changed