Fix typo in spf.md
Fix typo in spf.md

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