Documentation: asciidoc formatting fix for git-cvsexportcommit doc.
Documentation: asciidoc formatting fix for git-cvsexportcommit doc.

Annoyingly enough, asciidoc wants the same number of '=' on the second
line as there are characters on the first line.

Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git