Exercise doc button and forum button better open a new window

[jmplaza]

... instead of opening at the same tab, hiding the code+execution page. This way the webpage with the user's source code remains ready to use, and the user experience is improved.

A new window maybe better than a new tab, as people with two screens may also benefit from it using one window for the code+execution webpage and another one for the user documentation for that RoboticsAcademy exercise (HAL API description, GUI API description)

[ango1994]

Closed on #2236

[pawanw17]

Reopening this because of the superthin refactoring

[espilya]

@pawanw17 I tested the exercises and didnt find this issue in them

[pawanw17]

@espilya closing this