How to update website metadata using just markdown?

Hi everyone,
I am using a readme markdown file on the Github desktop site to create a single page website. How can I update my website’s metadata using just markdown? And/or what HTML code can I copy paste into the readme to update the metadata? My website is using the default theme layout. Currently, when my website shows on Google, the title of the website and description is not what I want it to be.

maybe this is what you mean.

Ex :

title: "Hugo Tutorial"
date: 2019-10-22T04:42:10+07:00
draft: false
tags : [

I made this code when creating a new post on my website. a website built on GoHugo.
You can see references on the Stackoverflow site

Hi, thanks for this. Two questions:

i. if I write just the code you suggest on the markdown readme file, does it do the changes or do I also need to add some code to the _layout file for the website? 

ii. are the “tags” the same thing as the description of the website on google?