Update the instruction for GitHub Pages

[sinsukehlab]

corresponding to the changes in UI

Why:

The UI of GitHub Pages has changed. Closes #10

Discussed in https://github.com/orgs/skills/discussions/105

^{Originally posted by **dkrasne** October 31, 2022} Here are a few hitches I ran into while setting up GitHub Pages from the tutorial: 1. Under 'how to start this course,' the screenshot is from introduction-to-github, not github-pages. It's not clear whether one should choose the name of one's future blog address, or if it makes sense to leave the default name of github-pages. This should be clarified. 2. Step 1, instruction 3 ("Click Pages, in the "GitHub Pages" section, use the Source drop-down, then select main branch.") did not match exactly what I saw. 'Main branch' was not an option under the Source drop-down; the only option other than GitHub Actions was "Deploy from a Branch". The **SECOND** drop-down menu (under Branch, not Source) gave "main" as an option. 3. I'm concerned that because of one or both of these unclear instructions, I did something wrong at some point, because when I go to my new page (currently at https://dkrasne.github.io/github-pages/ although I plan to rename it if I can't figure this out), the bottom of the page reads: "github-pages" and "Lesson on building a blog with Jekyll". So I think I _must_ have done something wrong (especially since I had to search for the button to merge the pull request, it didn't show up automatically), but I can't figure out where, since I followed all of the subsequent instructions precisely. 4. Even if I actually did everything correctly, those two unclear instructions should be changed, for the sake of beginners. Help would be appreciated, thanks!

What's being changed:

Step 1, the instruction for GitHub Pages

Check off the following:

• [x] For workflow changes, I have verified the Actions workflows function as expected.
• [x] For content changes, I have reviewed the style guide.

[sinsukehlab]

I forgot to check the issue #10. I add a commit now.

[purvac]

I concur with the observations made by @sinsukehlab and request the team to review the pull request asap.