First version of angr courses - WIP

Added symbolic write example.

Update simuvex.md

Fix typo "containts" -> "contains"

* Add HackCon example
* Remove useless variables

Signed-off-by: Stanislas P1kachu Lejay <p1kachu@lse.epita.fr>

`avoid`ed => `avoided`

Added test() to pass CI checks, added comments for clarity, and changed pg.explore() to use functions instead of addresses..

Troubleshooting steps added

fix typo

fix typo in example in states.md