Progress in the nasty divorce involving Kim Zolciak and Kroy Biermann ... it appears they've hammered out a child custody agreement ... but it's only temporary. The estranged couple sat down for a mediation session Tuesday last week, according to new legal docs obtained by TMZ ... which resulted in a temporary custody agreement signed by Kim and Kroy. It's unclear what the custody agreement entails ... all the docs say is they signed a deal. Kim and Kroy have four minor children ... sons KJ ,