I agree that this needs revision. I think the right way to do this would be to re-do the building of the http streamer inside the same workspace as the rest of the components that need to be built from source (currently rosbridge_suite, task_manager, task_msgs).
I wouldn't do this in the turtlebot2 while we're in the middle of demos, but you can try building (although probably not running) on another computer while developing the documentation for all this.
Finally, remember this both http_streamer and rosbridge_suite should be soon available via debians, so this is not very urgent since it may become obsolete when they become available, and that may be soon.