Revise the readme.md with more clear steps.

[mruac]

Hi, I just discovered this today and took a while trying to get this script working with the Google Apps Script layout in 2021 (also using it for the first time too!). Because of this I'd like to suggest the revised readme.md - though I have not had the chance to modify the script to send the correct Deployment IDs in the url.
Reading the OAuth1 Callback Url section helped me to find the callback url to use in the Twitter Authentication settings page.

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2. Configure your Google Script

• Click here to copy the Twitter RSS script into your Google Drive by going to Overview > Make a copy in the sidebar.
• Replace the placeholders for TWITTER_CONSUMER_KEY and TWITTER_CONSUMER_SECRET near the top of the file with the keys you took note of.
• Replace the placeholder for SCRIPT_PROJECT_KEY with the value from Project settings in the sidebar.
• Add https://script.google.com/macros/d/SCRIPT_PROJECT_KEY/usercallback as the callback URL in Authentication Settings > 3-legged OAuth in Twitter app settings. Add any url as the Website Url.

3. Deploy the Twitter RSS Feed generator

• Go to Run and an email will be sent to your google account's email address with a link to twitter to grant the app the necessary permissions. If you don't get the email, you can get the link from the Execution Log.
• After clicking that, do Run -> Start again and you’ll get an email with links to some sample RSS feeds.
• Go to Publish -> Deploy as Web App and choose Anyone, even anonymous under Who has Access. Click the Deploy button. The web app url is the feed url to use.

[jpowellrussell]

Thanks very much @mruac, this was tremendously helpful.