astro/xearth: add myself (nxjoseph) to freebsd.committers.markers

[nxjoseph]

Summary

I have used $ sort -n -r -k2 to put it with the right order. Thanks in advance.

$ sort -n -r -k2 astro/xearth/files/freebsd.committers.markers | grep -B1 -A1 nxjo
 32.754166,     34.963611,      "akiyano"                       # Tirat Carmel, Israel
 41.4507,       31.792,         "nxjoseph"                      # Zonguldak, Turkey
 50.430417,     30.488262,      "kib"                           # Kiev, Ukraine

[osa]

LGTM