fix broken links in User Guide index
fix broken links in User Guide index

sendgrid/docs,bogdanboss/docs,Zaftula/docs,bogdanboss/docs,GilUpstream/docs,Zaftula/docs,hardikjain29/docs,bogdanboss/docs,Zaftula/docs,Zaftula/docs,taz77/docs,L2G/docs,hardikjain29/docs,sendgrid/docs,Whatthefoxsays/docs,Aonepathan/docs,bogdanboss/docs,jacobmovingfwd/docs,Aonepathan/docs,katieporter/docs,awwa/docs,bogdanboss/docs,Zaftula/docs,L2G/docs,Aonepathan/docs,hardikjain29/docs,GilUpstream/docs,katieporter/docs,ksigler7/docs,taz77/docs,Aonepathan/docs,GilUpstream/docs,Ranhiru/docs,jacobmovingfwd/docs,katieporter/docs,taz77/docs,Ranhiru/docs,awwa/docs,taz77/docs,L2G/docs,hardikjain29/docs,GilUpstream/docs,Ranhiru/docs,jacobmovingfwd/docs,Aonepathan/docs,L2G/docs,hardikjain29/docs,ksigler7/docs,Whatthefoxsays/docs,jacobmovingfwd/docs,awwa/docs,ksigler7/docs,taz77/docs,katieporter/docs,Ranhiru/docs,Whatthefoxsays/docs,jacobmovingfwd/docs,Ranhiru/docs,GilUpstream/docs,L2G/docs,awwa/docs,katieporter/docs,awwa/docs,sendgrid/docs