Update READMEs to add details on building playground and katas

[Manvi-Agrawal]

Add instructions about building katas locally by building playground

[Manvi-Agrawal]

@tcNickolas need advice on following points:

1. Do you think we should have a README for samples folder? Currently, I don't see any README there.
2. How about a short section of how to migrate katas from old repository to the new one? I think following things will help:

• Sample PR
• Dont include images for now, since they need redesign.
• Look out for API name changes, if any.
• Change link to new QDK documentation.
• Get away with relative links for mentioning other katas or previous tasks, describe the things instead

[tcNickolas]

Looks good, I suggested a few small edits.

Thank you!

[tcNickolas]

@tcNickolas need advice on following points:

1. Do you think we should have a README for samples folder? Currently, I don't see any README there.
2. How about a short section of how to migrate katas from old repository to the new one? I think following things will help:

1. I would not add it for now - the samples folder is rather self-descriptive and doesn't have any special build instructions or knowledge associated with it. The one sub-folder that is a bit trickier to navigate is estimation, but that one already has its own readme with more details about different samples.

2. Katas migration is going to be a very short endeavor - the Classic QDK is going to be deprecated in June, so we need to complete migration in about two months. (Plus a lot of katas will need a much more significant rework than that, some even won't be migrated.) So I wouldn't elaborate on it in the readme - the readme should focus on using the new katas and developing them, not on getting them from one specific source.

This information can be good to add to the migration issue, since it is focused specifically on migration and will be closed once that's complete.

[tcNickolas]

Looks good to me, we just need somebody who's an owner of the whole repo to sign off too

[tcNickolas]

Urgh, looks like Prettier is not happy with one of the files, can you take a look to fix? Probably a missing newline somewhere

[Manvi-Agrawal]

Todo: update hyperlinks because of header change

PS: Done

[Manvi-Agrawal]

Urgh, looks like Prettier is not happy with one of the files, can you take a look to fix? Probably a missing newline somewhere.

Done

[minestarks]

Thank you for the updates!