Revision 307416

MFC r306718:
Add history section for echo(1)
Sourced using the draft copy of the second edition manual
http://www.tuhs.org/Archive/PDP-11/Distributions/research/1972_stuff/unix_2nd_edition_manual.pdf

PR:             211785
Approved by:    bcr (mentor)
Differential Revision:  https://reviews.freebsd.org/D8104