Added 'About This Guide' section

[borjasotomayor]

I've added a new section called 'About This Guide' that includes two pages:

• Report an Issue: Contains instructions on how to report typos, errors in the examples, etc.
• Acknowledgements: List of people who have directly or indirectly contributed to the guide

Here are a few specific things to review/discuss:

• Do we want to add any other issue categories in "Report an Issue"?
• I think it would be worthwhile to have a separate "Contributing to this Guide" page that is more focused on explaining how to clone the guide repository, install the necessary software (Sphinx, etc.), build the guide, etc. for anyone who actually wants to work on adding a new page or section to the guide. I think that can be a separate effort, though.
• We are separately going to work on a "Getting Help" section that focuses on how to get help in a class, but I wonder whether we want to set up some sort of support mechanism for anyone who is reading this guide outside the context of a specific class. e.g., we could set up an Ed Discussion site just for this guide (while also pointing out that, if they were pointed to any of the tutorials from a CS class, they should use the support mechanisms provided in that class)
• Are we missing any names in the Acknowledgements section?

[ar0r]

This draft looks great. As for names to add, I'd probably include Hannah.

With this page done, I think we can drop the Acks from the other pages.

Also, the style guide had acknowledgement when it was a 121 page. I noticed that has been dropped. I wonder if it makes sense to add it here.

[ar0r]

I forgot to answer the question about people who need help, but are not in a specific class. I suggest we point people to a channel on the CS Slack or to a CS Discord channel rather than creating an Ed Discussion site.

[borjasotomayor]

I've added a "Getting Help" page that describes how to get support on Slack or Discord (I've also created the relevant channels). Once this PR and PR #14 are merged, I'll add a note at the top that says something like "This page describes how to get help with this guide. We also have pages that describe how to get help in your classes" (and viceversa)