README: use full file names for default.xml and default-notools.xml
README: use full file names for default.xml and default-notools.xml

Passing 'default' or 'default-notools' to repo init's -m parameter fails because
the manifests are actually called 'default.xml' and 'default-notools.xml'
respectively.

Signed-off-by: Aaron Plattner <7c39395e2e801146cdbd7fb4a41282e4f38db44e@nvidia.com>
Signed-off-by: Stephen Warren <5ef2a23ba3aff51d1cfc8c113c1ec34b608b3b13@nvidia.com>

NVIDIA/tegra-uboot-flasher-scripts