pmap: add pmap_kextract(9) man page

[freebsd_igalic.co]

Summary

add a man page for pmap_kextract(9), with alias to vtophys(9).
This man page is based on pmap_extract(9).

[pauamma_gundo.com]

share/man/man9/pmap_kextract.9

3

SDPX ID for new files, per https://docs.freebsd.org/en/articles/license-guide/#pref-license.

50

56

59

61

[freebsd_igalic.co]

address @pauamma_gundo.com comments

[freebsd_igalic.co]

once again, i have broken a revision by trying to update it.