Remove big files from the repository and git history

[Risto97]

Currently, there are big files that are tracked that make the repository 13MB when freshly cloned.
It's mostly video files from documentation examples.
These files should be hosted somewhere else.

Git history needs to also be cleaned:

...
108K	./examples/verilator
108K	./tests
132K	./cmake/sim
220K	./examples
404K	./docs/static/img
564K	./cmake
632K	./docs/source/graphics
636K	./docs/source
2,7M	./docs/static/examples
3,1M	./docs/static
5,6M	./docs
5,9M	./.git/objects
5,9M	./.git/objects/pack
6,1M	./.git
13M	.