cmake: building doc is now a cmake option and off by default
cmake: building doc is now a cmake option and off by default

Signed-off-by: Brendan Le Foll <3e0e8c4069934e8b47d99704927a85c66c0ceb33@intel.com>

g-vidal/mraa,sergev/mraa,yangjae/mraa,alexandru-elisei/mraa,jontrulson/mraa,seem-sky/mraa,yoyojacky/mraa,petreeftime/mraa,STANAPO/mraa,sergev/mraa,timrtoo/Intel,Propanu/mraa,nioinnovation/mraa,damcclos/mraa,sundw2014/mraa,mircea/mraa,malikabhi05/mraa,arunlee77/mraa,neuberfran/mraa,g-vidal/mraa,yoyojacky/mraa,ncrastanaren/mraa,allela-roy/mraa,nioinnovation/mraa,Propanu/mraa,noahchense/mraa,seem-sky/mraa,pctj101/mraa,stefan-andritoiu/mraa,KurtE/mraa,zBMNForks/mraa,Propanu/mraa,sergev/mraa,noahchense/mraa,KurtE/mraa,spitfire88/mraa,tripzero/mraa,seem-sky/mraa,timrtoo/Intel,alext-mkrs/mraa,Pillar1989/mraa,smileboywtu/mraa,stefan-andritoiu/mraa,SyrianSpock/mraa,neuroidss/mraa,intel-iot-devkit/mraa,w4ilun/mraa,sundw2014/mraa,jontrulson/mraa,STANAPO/mraa,ncrastanaren/mraa,tripzero/mraa,noahchense/mraa,stefan-andritoiu/mraa,neuberfran/mraa,alexandru-elisei/mraa,neuberfran/mraa,malikabhi05/mraa,seem-sky/mraa,petreeftime/mraa,anonymouse64/mraa,whbruce/mraa,neuroidss/mraa,Kiritoalex/mraa,pctj101/mraa,SyrianSpock/mraa,KurtE/mraa,damcclos/mraa,noahchense/mraa,stefan-andritoiu/mraa-gpio-chardev,ncrastanaren/mraa,whbruce/mraa,timrtoo/Intel,yangjae/mraa,ncrastanaren/mraa,arfoll/mraa,Hbrinj/mraa,Hbrinj/mraa,zBMNForks/mraa,yangjae/mraa,alext-mkrs/mraa,petreeftime/mraa,Kiritoalex/mraa,w4ilun/mraa,STANAPO/mraa,jontrulson/mraa,intel-iot-devkit/mraa,alexandru-elisei/mraa,intel-iot-devkit/mraa,arfoll/mraa,ProfFan/mraa,Propanu/mraa,mircea/mraa,alexandru-elisei/mraa,stefan-andritoiu/mraa,yongli3/mraa,ProfFan/mraa,smileboywtu/mraa,andreivasiliu2211/mraa,stefan-andritoiu/mraa-gpio-chardev,stefan-andritoiu/mraa-gpio-chardev,neuberfran/mraa,nioinnovation/mraa,yongli3/mraa,pctj101/mraa,jontrulson/mraa,stefan-andritoiu/mraa-gpio-chardev,alext-mkrs/mraa,ProfFan/mraa,Hbrinj/mraa,petreeftime/mraa,damcclos/mraa,arunlee77/mraa,intel-iot-devkit/mraa,Meirtz/mraa,timrtoo/Intel,noahchense/mraa,Meirtz/mraa,andreivasiliu2211/mraa,sundw2014/mraa,jontrulson/mraa,whbruce/mraa,sergev/mraa,spitfire88/mraa,yoyojacky/mraa,matt-auld/mraa,alext-mkrs/mraa,KurtE/mraa,tripzero/mraa,malikabhi05/mraa,arfoll/mraa,KurtE/mraa,Pillar1989/mraa,Pillar1989/mraa,intel-iot-devkit/mraa,anonymouse64/mraa,alex1818/mraa,SyrianSpock/mraa,spitfire88/mraa,anonymouse64/mraa,andreivasiliu2211/mraa,malikabhi05/mraa,g-vidal/mraa,arfoll/mraa,yongli3/mraa,ProfFan/mraa,arunlee77/mraa,malikabhi05/mraa,seem-sky/mraa,ncrastanaren/mraa,neuberfran/mraa,alex1818/mraa,allela-roy/mraa,neuroidss/mraa,Propanu/mraa,g-vidal/mraa,stefan-andritoiu/mraa-gpio-chardev,whbruce/mraa,spitfire88/mraa,alext-mkrs/mraa,g-vidal/mraa,zBMNForks/mraa,Kiritoalex/mraa,Jon-ICS/mraa,arunlee77/mraa,Meirtz/mraa,andreivasiliu2211/mraa,matt-auld/mraa,Jon-ICS/mraa,Hbrinj/mraa,yongli3/mraa,alex1818/mraa,stefan-andritoiu/mraa,w4ilun/mraa,mircea/mraa,arfoll/mraa,Jon-ICS/mraa,pctj101/mraa,smileboywtu/mraa,yongli3/mraa,alexandru-elisei/mraa,matt-auld/mraa,allela-roy/mraa,sundw2014/mraa,sergev/mraa,timrtoo/Intel,sundw2014/mraa,yangjae/mraa,w4ilun/mraa,pctj101/mraa