Suggested by Glenn Morris in:
http://lists.gnu.org/archive/html/emacs-devel/2015-04/msg00678.html
* Makefile.in (install-man): Don't treat ChangeLog.1 as a man page.
* doc/man/ChangeLog.1: Rename back from doc/man/ChangeLog.01.
* lisp/erc/ChangeLog.1: New file, containing the old contents of ...
* lisp/erc/ChangeLog.01, lisp/erc/ChangeLog.02, lisp/erc/ChangeLog.03:
* lisp/erc/ChangeLog.04, lisp/erc/ChangeLog.05, lisp/erc/ChangeLog.06:
* lisp/erc/ChangeLog.07, lisp/erc/ChangeLog.08, lisp/erc/ChangeLog.09:
Remove.