docs: explain how to build cdn js file #11042
                
   Open
            
            
          
  Add this suggestion to a batch that can be applied as a single commit.
  This suggestion is invalid because no changes were made to the code.
  Suggestions cannot be applied while the pull request is closed.
  Suggestions cannot be applied while viewing a subset of changes.
  Only one suggestion per line can be applied in a batch.
  Add this suggestion to a batch that can be applied as a single commit.
  Applying suggestions on deleted lines is not supported.
  You must change the existing code in this line in order to create a valid suggestion.
  Outdated suggestions cannot be applied.
  This suggestion has been applied or marked resolved.
  Suggestions cannot be applied from pending reviews.
  Suggestions cannot be applied on multi-line comments.
  Suggestions cannot be applied while the pull request is queued to merge.
  Suggestion cannot be applied right now. Please check back later.
  
    
  
    
I was trying to figure out how to re-build the same file that is served from CDNs, and I got confused and tripped over myself on the way. through my own mistakes, I had actually convinced myself that the build script in this repo did not produce the file that the CDN was serving. Nothing in the docs talked about it, so I just assumed it was some "special thing that exists somewhere else."
I am adding this to the docs now so that the next person reading through will be re-assured and hopefully find the right file.