When Telemetry is disabled the about:telemetry screen first line of display is:
> Please set toolkit.telemetry.enabled to true in about:config
(<i>about:config</i> is underlined and in blue)
Users may expect about:config to be an active link as it is shown as blue underlined text.
It would be more user friendly to use the UI menu "Options" & or explain the use of about protocols & about:config.
This could be explained in the text, as a prior suggestion and probably explained by adding a link to the Firefox kb article https://support.mozilla.com/en-US/kb/Options%20window%20-%20Advanced%20panel?as=u#w_general-tab
One suggestion for the sort of revised text I envisage
> If you wish to re-enable sending telemetry data please use:
> about:config (advanced users)
> or the Options window https://support.mozilla.com/en-US/kb/Options%20window%20-%20Advanced%20panel?as=u#w_general-tab
about:telemetry isn't an official thing, but when it becomes so, it should certainly have something like this.
*** This bug has been marked as a duplicate of bug 661881 ***