Reword explanation about why XHR is used instead of the builtin extension updater
Explain that the header and footer need to be removed from the signature file
Specify update checking wait interval in terms of milliseconds
Mention the fact that the way error reports is to be handled hasn't been determined
Better wording for how update is applied and reference to pseudocode
Change date format to dd-mm-yyyy
Update pseudocode with some more security checks and reference to the repeated request attempts