Correct SetMatrix documentation

The SetMatrix is a generic data structure, so the description
should not be tight to any specific use

Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
(cherry picked from commit 898e321)

common/setmatrix.go

@@ -10,23 +10,23 @@ import (
 type SetMatrix interface {
 	// Get returns the members of the set for a specific key as a slice.
 	Get(key string) ([]interface{}, bool)
-	// Contains is used to verify is an element is in a set for a specific key
+	// Contains is used to verify if an element is in a set for a specific key
 	// returns true if the element is in the set
 	// returns true if there is a set for the key
 	Contains(key string, value interface{}) (bool, bool)
-	// Insert inserts the mapping between the IP and the endpoint identifier
-	// returns true if the mapping was not present, false otherwise
-	// returns also the number of endpoints associated to the IP
+	// Insert inserts the value in the set of a key
+	// returns true if the value is inserted (was not already in the set), false otherwise
+	// returns also the length of the set for the key
 	Insert(key string, value interface{}) (bool, int)
-	// Remove removes the mapping between the IP and the endpoint identifier
-	// returns true if the mapping was deleted, false otherwise
-	// returns also the number of endpoints associated to the IP
+	// Remove removes the value in the set for a specific key
+	// returns true if the value is deleted, false otherwise
+	// returns also the length of the set for the key
 	Remove(key string, value interface{}) (bool, int)
-	// Cardinality returns the number of elements in the set of a specfic key
-	// returns false if the key is not in the map
+	// Cardinality returns the number of elements in the set for a key
+	// returns false if the set is not present
 	Cardinality(key string) (int, bool)
 	// String returns the string version of the set, empty otherwise
-	// returns false if the key is not in the map
+	// returns false if the set is not present
 	String(key string) (string, bool)
 }