repo: Capitalize role names in signed metadata
repo: Capitalize role names in signed metadata

Signed-off-by: Lewis Marshall <748e1641a368164906d4a0c0e3965345453dcc93@lmars.net>

endophage/gotuf,cyli/gotuf,diogomonica/gotuf,dmcgowan/gotuf,runcom/gotuf,theupdateframework/go-tuf