Commit ddf335 added the ability to support erlang's new release naming c...

...onvention; but it also broke support for relases that begin with 'R'.  Removing this sed command fixes.

I'm not a sed master; but it looks like that command removes the R from the releases. .kerl/otp_releases file goes from looking like this

R10B-0
R10B-10
R10B-1a
...
17.0
17.0-rc1
17.0-rc2

To looking like this