Typo and small content change inside help

Go to Help -> Adding Qt Versions

The way to add new Qt versions has changed since the options dialog has changed.

Go to Help -> Adding Tool Chains

The way to add new Tool chains has changed since the options dialog has changed.
Here is also a small typo: the bold "Build Settings" is missing a 'g'

=> for both there is now a single tab (Build & Run) and you can switch there to Qt Versions or Tool Chains