add extension points for the theme users to add their own CSS and JS.

[hatappo]

I would like to have extension points for Theme users to add their own CSS and JS.

There is a custom_js block in base.html, but this is already used by Theme itself as an extension to page.html, etc., so it doesn't seem to be intended as an extension for Theme users.

It would be nice if you could suggest a better naming for the Tera blocks.

(I am always so grateful for your wonderful work. I especially love the Mermaid and Chart Shortcodes. Thank you.)

[RatanShreshtha]

thanks