r2e.1: Properly escape an ellipsis in the sample configuration

Following the example from nroff.1, which uses:

  .RI [ file\~ .\|.\|.]

For reasons that I haven't bothered to track down, the ellipsis isn't
rendered correctly when it occurs at the beginning of a line (even
with the `\|` separators).  After adding some leading whitespace,
everything seems to be working fine.

Reported-by: Matěj Cepl <mcepl@redhat.com>
Signed-off-by: W. Trevor King <wking@tremily.us>