docs: minor cleanup to simulation docs (backport #21777) (#21796)

Co-authored-by: Marko <marko@baricevic.me>

types/simulation/collections.go

@@ -10,6 +10,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/types/kv"
 )
 
+// NewStoreDecoderFuncFromCollectionsSchema returns a function that decodes two kv pairs when the module fully uses collections
 func NewStoreDecoderFuncFromCollectionsSchema(schema collections.Schema) func(kvA, kvB kv.Pair) string {
 	colls := schema.ListCollections()
 	prefixes := make([][]byte, len(colls))