Change app.js and README to better reflect actual solution code

[meldaravaniel]

Working through the codeLab on https://webrtc.org/getting-started/firebase-rtc-codelab, I discovered the instructions and the app.js in the codelab were different enough from the solution as to be difficult to follow. I took the solution's code, copied it into the lab code and removed sections accordingly. Also modified the solution's code to include a function the instructions talked about (see forthcoming pull request to the solution branch).

Finally, I copied all the instructions into the README and corrected them to reflect what the solutions code actually contains, some differences in Firestore, and added tips on how to do this if you're using git-bash.

I would correct the actual instructions on the website, but I don't think I have access. So adding it to the README seemed a close second, though annoying that they'll be out of sync for a bit.

[meldaravaniel]

@guidou I'm going to pick on you, since it looks like you've been working on the Samples project for WebRTC and it won't let me @ anyone else 😅 Do you know who should be contacted for PR approval for this codelab? It looks like there are a few pending PRs hanging out, but I would recommend not merging #24 as I've corrected app.js to basically include that, but also make it match the actual solution code. #25 is just a typo fix, so that merge is probably fine.

I would also love to update the actual text of the instructions on the codelab, but I didn't see a contribution link for that one, so I settled for the README.

I'd also like to test this, but I didn't have the time at the moment, apologies.

It does seem like there's a steady drip of folks trying to use the codelab and they're all getting frustrated with it. This would really help.

Edited to add: oh derp. Found the repo for the website...whelp. Off to go make more PRs. :D

Edit 2: nvm that's the old site, deprecated.

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[meldaravaniel]

@natkuhn now that you're in on this 😈 *evil laugh* 😈 the PR needs a CLA signature from you before it can be merged (if that ever happens ;P ). It's a standard requirement for contributions merged into Google-related repos. See above instructions from the cla bot.

[natkuhn]

@meldaravaniel all done but I am guessing you should be the one to comment @googlebot I fixed it.? [Edit: I just went ahead and did it.] The other change I thought of, but forgot to mention, is to make the command lines without sh be the default. Wasn't sure why it said git-bash rather than just bash, etc. Not sure who would need the sh.

[natkuhn]

@googlebot I fixed it.

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[natkuhn]

@googlebot I consent.

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[meldaravaniel]

...make the command lines without sh be the default. Wasn't sure why it said git-bash rather than just bash, etc. Not sure who would need the sh.

@natkuhn yeah that's reasonable. I use gitbash, so I wrote that for myself, but you're probably right it's not necessary to specify that fine-grained.