Docs: Update the Contributing Guidelines

[adiati98]

Description

As part of Intro to OSS course, the contributing guidelines in this guestbook repo is following and being adjusted from the guidelines at the intro repository. But as the intro repository evolves, the contributing guidelines in this repo is no longer 100% accurate. Therefore, it needs to be updated.

Another reason is as Hacktoberfest is approaching, we want to make this repo ready for contributions not only from the course participants, but also from folks who don't take our Intro to OSS course.

Suggested Solution

Alternative 1

Update the contributing guidelines by adding instructions from Let's Get Practical section and adjust other sections accordingly.

Alternative 2

Remove the contributing guidelines completely with below reasons:

• We have the Getting Started section on the README that navigate folks to the instructions of adding themselves to the guestbook.
• The Contributing section on the README already holds the information for folks to improve our Intro to OSS course.

[adiati98]

@BekahHW I need your thoughts on this. Thank you.