Update sr.coffee (#3733)
Update sr.coffee (#3733)

- fixed some typos and language flow issues
- translated more sections and started courses section
probil/codecombat,codecombat/codecombat,edtrist/codecombat,tpai/codecombat,jeremiahyan/codecombat,kidaa/codecombat,Zerrien/codecombat,VilkkuV/codecombat,edtrist/codecombat,codecombat/codecombat,fabichoi/codecombat,kidaa/codecombat,javatlacati/codecombat,icodegame/codecombat,javatlacati/codecombat,probil/codecombat,VilkkuV/codecombat,VilkkuV/codecombat,duybkict/codecombat,jeremyprice/codecombat,Zerrien/codecombat,VilkkuV/codecombat,edtrist/codecombat,icodegame/codecombat,tpai/codecombat,probil/codecombat,icodegame/codecombat,javatlacati/codecombat,fabichoi/codecombat,codecombat/codecombat,Zerrien/codecombat,jeremyprice/codecombat,jeremiahyan/codecombat,codecombat/codecombat,tpai/codecombat,jeremiahyan/codecombat,duybkict/codecombat,fabichoi/codecombat,jeremyprice/codecombat,codecombat/codecombat,jeremiahyan/codecombat,duybkict/codecombat,duybkict/codecombat,probil/codecombat,edtrist/codecombat,icodegame/codecombat,kidaa/codecombat,kidaa/codecombat,javatlacati/codecombat,javatlacati/codecombat,tpai/codecombat,jeremyprice/codecombat,fabichoi/codecombat,Zerrien/codecombat