you can read all 5 pages of the sticky.. but stocking knit curls
(dogs pant, humans sweat, the sun rises in the east and sets in the west) some things just are.
edging helps, but you need a deep edging an inch or two on a afgan isn't going to do much to stop curling!
you can line the blanket once its finished.
or you can double knit it,
or make a double sided blanket (a tube) and seam the cast on/bind off edges.
you can knit it loose and it will curl loosely (knit it tight and it will curl tightly!)
but stocking knit curls.
it is the nature of the stitch. you could work the blanket in the round, with alternate stripes (4 to 8 rows) of stocking knit and reverse stocking knit-making it reversible and none curling (actually its still curling, only the stocking knit want to curl one way and the reverse stocking knit the other and they balance out!)
there are wonderful things you can do with stocking knits nature to curl.. its an asset if used right..but you can't change the nature of the stitch.