Add TOC link for new `ElsePlacement` linter.

Change-Id: Idc08f70cb4bc0321e0511a5e5f5bed72a70ab2ab
Reviewed-on: http://gerrit.causes.com/40244
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Joe Lencioni <joe.lencioni@brigade.com>