remove-old-kernels - en to en_US translation catalogue (3 entries)

en:     -m = mono. No colours in screen output.
en_US:     -m = mono. No colors in screen output.

en:      X = keeping for (X)tables-addons (only in advanced mode)
en_US:      X = keeping for (X)tables-addons. (only in advanced mode)

en: y/N/i (i=confirm for each)
en_US: y/N/i (y=yes N=no i=confirm for each)
