Makefile.include: Explain usage of FORCE and PHONY.
Makefile.include: Explain usage of FORCE and PHONY.

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