linux: add jekyll install

Signed-off-by: Micky Ching <mickyching@gmail.com>
prog: add emacs org mode notes

Signed-off-by: Micky Ching <mickyching@gmail.com>
prog: add emacs usage

Signed-off-by: Micky Ching <mickyching@gmail.com>
prog: publish C++ exercises

Signed-off-by: Micky Ching <mickyching@gmail.com>