[skip ci] Check the syntax of timesync_md (#13390)

Signed-off-by: Nmin.tian <min.tian.cn@gmail.com>

docs/design_docs/milvus_timesync_en.md

@@ -33,7 +33,7 @@ Ideally, `u2` expects `C0` to be empty at `t2`, and could only see `A1` at `t7`;
 
 It's easy to achieve this in a `single-node` database. But for a `Distributed System`, such as `Milvus`, it's a little difficult; the following problems need to be solved:
 
-1. If `u1` and `u2` are on different nodes, and their time clock is not synchronized. To give an extreme example, suppose that the time of `u2` is 24 hours later than `u1`, then all the operations of `u1` can't been seen by `u2` until next day.
+1. If `u1` and `u2` are on different nodes, and their time clock is not synchronized. To give an extreme example, suppose that the time of `u2` is 24 hours later than `u1`, then all the operations of `u1` can't be seen by `u2` until next day.
 2. Network latency. If `u2` starts the `Search on C0` at `t17`, then how can it be guaranteed that all the `events` before `t17` have been processed? If the events of `delete A1 from C0` has been delayed due to the network latency, then it would lead to incorrect state: `u2` would see both `A1` and `A2` at `t17`.
 
 `Time synchronization system` is used to solve the above problems.