Merge the following from the English version. Note that an xref entity
is commemted out due to a not-translated-yet part in mirrors/chapter.sgml.
1.263 -> 1.274 handbook/ports/chapter.sgml
Submitted by: Ryusuke Suzuki <ryusuke _at_ jp dot FreeBSD dot org>
Reference: [doc-jp-work 1910, 1928, 1929]