Apply suggestions from code review

Co-Authored-By: longfin <longfinfunnel@gmail.com>

CHANGES.md

@@ -24,11 +24,11 @@ To be released.
     and its all implementations.  [[#189]]
  -  The signature of `IStore.PutBlock<T>(Block<T>)` method was changed to
     `PutBlock<T>(Block<T>, Address)`.  [[#189]]
- -  Improved the read throughput of `BlockChain<T>` when calling
+ -  Improved the read throughput of
     `BlockChain<T>.Append()`.
- -  Fixed a bug that `Swarm` attempted to use TURN relay even though `_host` was
+ -  Fixed a bug that `Swarm` had attempted to use TURN relay even if the `host` argument was
     given.
- -  Fixed a bug that TURN relay was disconnected when connecting for more than 5
+ -  Fixed a bug that TURN relay had been disconnected when being connected for longer than 5
     minutes.
 
 [#185]: https://github.com/planetarium/libplanet/pull/185