The console installer on 64-bit Linux shows the following message:

Installation of Confluence 6.9.1 is complete
Your installation of Confluence 6.9.1 is now ready and can be accessed via
your browser.
Custom modifications
Your previous Confluence installation contains customisations (eg
server.xml) that must be manually transferred. Refer to our documentation
more information:
http://docs.atlassian.com/confluence/docs-6.9.1/Upgrading+Confluence#UpgradingConfluence-custommodifications
Confluence 6.9.1 can be accessed at http://localhost:80

However, accessing the URL

http://docs.atlassian.com/confluence/docs-6.9.1/Upgrading+Confluence#UpgradingConfluence-custommodifications

Results in the following:

404 Not Found

• Code: NoSuchKey
• Message: The specified key does not exist.
• Key: atlassian-confluence/docs-6.9.1/Upgrading+Confluence
• RequestId: 8F338A20D40ED829
• HostId: aHrf211R4AftxonHXO6ATZ8PRLRv5b01GPuPu/Nah0PoYvvhTLuCkIjI+cHjAFc8lguM+Ju7e3Q=

An Error Occurred While Attempting to Retrieve a Custom Error Document

• Code: NoSuchKey
• Message: The specified key does not exist.
• Key: error.html