Broken links to videos and related materials

[jwakely]

At https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#rsvideo-videos-about-modern-c the first two links are to channel9.msdn.com which redirects to some generic landing page at learning.microsoft.com (@gdr-at-ms any idea if those videos still exist somewhere?)

At https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#rfcore-core-guidelines-materials the link to the slides for @cubbimew's talk is broken.

[BenjamenMeyer]

@jwakely Microsoft has a long history of not keeping links working after a few years; basically every time they do a redesign things tend to break.

[cubbimew]

fixed my slides in f51cbb3 , thanks for doing the boring work