Some Days Ago I Created a Repo on github at https://github.com/shriekdj/shriekdj.github.io And I got Some Issues With It Not With The Site Building But With It's Interaction With Google Search Console.
I Know It Was Small Site But Just For Learning I Used google search console.
Firstly It Will Ask You To add your site as a Property. Here property is term for verification of Website Ownership Who is submitting the site to google.
If You Can change the site's html the add the verification script in your
<head> tag of your site.
There is As part where you Have to add Sitemap to Google Search Console But You Also Had To add the Complete URL of Your Sitemap into robots.txt file.
FOR Jekyll Site You Need to add this things in your site.
robots.txtfile and also add the sitemap url in it
It Helps to Crawling of your site by Search Engine Bots.
.htaccessIn Your Site for In Future Your gonna give site a custom domain.
For 301 type redirection
CNAMEfile only if your starting to change the site doomain.