core/mbox: doc typo fixes
core/mbox: doc typo fixes

yogo1212/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,yogo1212/RIOT,miri64/RIOT,ant9000/RIOT,kaspar030/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,cladmi/RIOT,basilfx/RIOT,kbumsik/RIOT,josephnoir/RIOT,toonst/RIOT,mtausig/RIOT,biboc/RIOT,gebart/RIOT,gebart/RIOT,biboc/RIOT,kaspar030/RIOT,cladmi/RIOT,toonst/RIOT,jasonatran/RIOT,kYc0o/RIOT,lazytech-org/RIOT,basilfx/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,x3ro/RIOT,authmillenon/RIOT,mtausig/RIOT,mfrey/RIOT,kaspar030/RIOT,josephnoir/RIOT,cladmi/RIOT,rfuentess/RIOT,OTAkeys/RIOT,cladmi/RIOT,toonst/RIOT,kYc0o/RIOT,josephnoir/RIOT,RIOT-OS/RIOT,mfrey/RIOT,jasonatran/RIOT,josephnoir/RIOT,smlng/RIOT,A-Paul/RIOT,neiljay/RIOT,aeneby/RIOT,avmelnikoff/RIOT,gebart/RIOT,neiljay/RIOT,smlng/RIOT,kbumsik/RIOT,ant9000/RIOT,miri64/RIOT,authmillenon/RIOT,yogo1212/RIOT,neiljay/RIOT,RIOT-OS/RIOT,avmelnikoff/RIOT,gebart/RIOT,authmillenon/RIOT,avmelnikoff/RIOT,miri64/RIOT,A-Paul/RIOT,biboc/RIOT,A-Paul/RIOT,lazytech-org/RIOT,mfrey/RIOT,josephnoir/RIOT,biboc/RIOT,lazytech-org/RIOT,basilfx/RIOT,smlng/RIOT,avmelnikoff/RIOT,rfuentess/RIOT,rfuentess/RIOT,x3ro/RIOT,biboc/RIOT,BytesGalore/RIOT,kYc0o/RIOT,mtausig/RIOT,neiljay/RIOT,A-Paul/RIOT,aeneby/RIOT,BytesGalore/RIOT,OlegHahm/RIOT,OlegHahm/RIOT,mtausig/RIOT,aeneby/RIOT,gebart/RIOT,OTAkeys/RIOT,neiljay/RIOT,smlng/RIOT,aeneby/RIOT,kbumsik/RIOT,basilfx/RIOT,lazytech-org/RIOT,kYc0o/RIOT,authmillenon/RIOT,yogo1212/RIOT,toonst/RIOT,kaspar030/RIOT,OTAkeys/RIOT,mtausig/RIOT,BytesGalore/RIOT,jasonatran/RIOT,x3ro/RIOT,BytesGalore/RIOT,kbumsik/RIOT,rfuentess/RIOT,kYc0o/RIOT,ant9000/RIOT,authmillenon/RIOT,cladmi/RIOT,OTAkeys/RIOT,x3ro/RIOT,aeneby/RIOT,yogo1212/RIOT,OlegHahm/RIOT,lazytech-org/RIOT,mfrey/RIOT,miri64/RIOT,avmelnikoff/RIOT,toonst/RIOT,basilfx/RIOT,OlegHahm/RIOT,x3ro/RIOT,kbumsik/RIOT,ant9000/RIOT,ant9000/RIOT,mfrey/RIOT,miri64/RIOT,kaspar030/RIOT,BytesGalore/RIOT,yogo1212/RIOT,A-Paul/RIOT,jasonatran/RIOT,rfuentess/RIOT,OlegHahm/RIOT,smlng/RIOT