add optional steps to activate workflows and gh-pages after fork a lesson

[avallecam]

At episode Editing a {sandpaper} lesson, section Fork and Clone a Lesson, I noticed that, if the learner would like to visualize their changes in the website format, they would need to:

• Activate the "disabled" workflows in the Actions tab. (as in the image attached)
• Activate the GitHub Pages to build and deploy from gh-pages branch.

(Note: this workflow disactivation happened to another workbech-lesson that I forked last week)

This will be useful for people learning by forking other workbench repos different from the sandpaper-docs, which we currently can not activate GitHub Pages, and activating the workflows is not required.

[froggleston]

Thanks @avallecam ! We're in the process of planning and implementing changes to this documentation as it's out of date and not as clear as it could be.

We can address this as part of the upcoming changes to this documentation @tobyhodges.