refine comments for for four files (#5011)

* refine comments for cache.go

* refine comments for log.go

* Update orm.go

* refine comments for orm_log.go,types.go

* Update utils.go

* Update doc.go

* Update db.go

client/cache/cache.go

@@ -53,21 +53,21 @@ type Cache interface {
 	Get(ctx context.Context, key string) (interface{}, error)
 	// GetMulti is a batch version of Get.
 	GetMulti(ctx context.Context, keys []string) ([]interface{}, error)
-	// Set a cached value with key and expire time.
+	// Put Set a cached value with key and expire time.
 	Put(ctx context.Context, key string, val interface{}, timeout time.Duration) error
 	// Delete cached value by key.
 	// Should not return error if key not found
 	Delete(ctx context.Context, key string) error
-	// Increment a cached int value by key, as a counter.
+	// Incr Increment a cached int value by key, as a counter.
 	Incr(ctx context.Context, key string) error
-	// Decrement a cached int value by key, as a counter.
+	// Decr Decrement a cached int value by key, as a counter.
 	Decr(ctx context.Context, key string) error
-	// Check if a cached value exists or not.
+	// IsExist Check if a cached value exists or not.
 	// if key is expired, return (false, nil)
 	IsExist(ctx context.Context, key string) (bool, error)
-	// Clear all cache.
+	// ClearAll Clear all cache.
 	ClearAll(ctx context.Context) error
-	// Start gc routine based on config string settings.
+	// StartAndGC Start gc routine based on config string settings.
 	StartAndGC(config string) error
 }