corrected Table of Contents instructions

[gregfitzgerald]

In the README, the developer says:

You can add a table of contents by supplying the toc: true param to your post front matter. If you want a border around it you can also set tocBorder: true.

The correct params would actually be toc = true and tocBorder = true.

[underscoreHao]

The description is not wrong. There are a couple of supported formats: YAML, TOML, JSON - https://gohugo.io/content-management/front-matter/