Add SPD coursepage (#1225)

* Create README.md

* Add files via upload

* Update README.md

* Add files via upload

* Update README.md

* Update README.md

* Update readings.md

* Update README.md

* Update README.md

* Delete coursepages/spd/HTC2X.zip

* Delete coursepages/spd/htc-simple.zip

* Delete coursepages/spd/space-invaders-starter.rkt

* Delete coursepages/spd/ta-solver-starter.rkt

* Update README.md

* Add files via upload

* Add info about eabling automatic parentheses, square brackets and quotes