fix ThreadSafeContext lock/unlock function names

src/module.c

@@ -4740,9 +4740,9 @@ int RM_BlockedClientDisconnected(RedisModuleCtx *ctx) {
  *
  * To call non-reply APIs, the thread safe context must be prepared with:
  *
- *     RedisModule_ThreadSafeCallStart(ctx);
+ *     RedisModule_ThreadSafeContextLock(ctx);
  *     ... make your call here ...
- *     RedisModule_ThreadSafeCallStop(ctx);
+ *     RedisModule_ThreadSafeContextUnlock(ctx);
  *
  * This is not needed when using `RedisModule_Reply*` functions, assuming
  * that a blocked client was used when the context was created, otherwise