doc: fix a markdown error in CTC meeting minutes

This fixes a markdown formatting error in 2016-07-13 CTC meeting
minutes, __proto__ was rendered incorrectly.

This was found by remark-lint.

PR-URL: https://github.com/nodejs/node/pull/7729


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Robert Jefe Lindstaedt <robert.lindstaedt@gmail.com>