Links for c++ examples broken in documentation

[joansola]

In the documentation page:

https://artivis.github.io/manif/cpp/index.html

the links for the c++ examples are broken. For example, the link for the se2_localization.cpp file states:

https://artivis.github.io/manif/cpp/examples/se2_localization.cpp

while the true link should be e.g.:

https://github.com/artivis/manif/blob/devel/examples/se2_localization.cpp

maybe changing devel by some other branch.