added description of Social Media module
added description of Social Media module

Updated /User_Guide/Marketing_Campaigns/drag_drop.html to include description of the social media icons module with example HTML code.
ksigler7/docs,katieporter/docs,hardikjain29/docs,Aonepathan/docs,Zaftula/docs,Aonepathan/docs,hardikjain29/docs,sendgrid/docs,Aonepathan/docs,jacobmovingfwd/docs,sendgrid/docs,jacobmovingfwd/docs,hardikjain29/docs,ksigler7/docs,katieporter/docs,Whatthefoxsays/docs,jacobmovingfwd/docs,katieporter/docs,Whatthefoxsays/docs,jacobmovingfwd/docs,Zaftula/docs,katieporter/docs,Whatthefoxsays/docs,hardikjain29/docs,Zaftula/docs,katieporter/docs,ksigler7/docs,sendgrid/docs,Zaftula/docs,jacobmovingfwd/docs,Aonepathan/docs,Zaftula/docs,Aonepathan/docs,hardikjain29/docs