From the document mentioned:
"• Once the opposing team is behind the build out line, the goalkeeper can pass, throw or roll the ball into play (punts and drop kicks are not allowed)"
As already explained, it is not in the laws of the game because this doesn't belong there. It is an adaptation for when playing 7v7.
Also, the documentation is not meant to teach you English; they are written with the assumption you understand it. If you go to the Merriam Dictionary, you'll find that one of the definitions (the one that applies to this case) reads as:
Punt:
transitive verb
: to kick (something, such as a football or soccer ball) with the top of the foot before the ball which is dropped from the hands hits the ground
I hope this helps.