Fix typo in redis.h

Closes #1386

src/redis.h

@@ -499,7 +499,7 @@ typedef struct readyList {
 } readyList;
 
 /* With multiplexing we need to take per-client state.
- * Clients are taken in a liked list. */
+ * Clients are taken in a linked list. */
 typedef struct redisClient {
     uint64_t id;            /* Client incremental unique ID. */
     int fd;