Time to first response gadget is linking to a defunct help page
Tested in Jira server 7.6.0 with charting plugin 2.3.0
Add dashboard gadget "Time to first response"
Select a filter that does not have any issues that match
The page presents a red box explaining this won't work, but here is a link to click to learn how to fix this
Click that link with the text
Would expect to be directed to a documentation page that explains how to use this particular charts functionality
Page does not load. It appears that this page/space no longer exists http://confluence.atlassian.com/display/JIRAEXT/JIRA+Charting+Plugin. This specific link no longer works.
It looks like the entire space no longer exists. So I suspect this is probably just something that should be updated in the plugin to reflect the new documentation space here to help customers
In the meantime, I think you could use KB https://confluence.atlassian.com/jirakb/time-to-first-response-gadget-does-not-display-data-779160763.html as a means to understand what is needed for this feature to work.