changelog for fast sync default (#1045)

Signed-off-by: Ratan Rai Sur <ratan.r.sur@gmail.com>

CHANGELOG.md

@@ -1,6 +1,6 @@
 # Changelog
 
-## Breaking change upcoming in v1.5 
+## Breaking change upcoming in v1.5
 
 To maintain best security practices, we're changing the `user:group` on the Docker container to `besu`.
 
@@ -18,6 +18,11 @@ If you’re mounting local folders, it is best to set the user via the Docker `
 UID because the username may not exist inside the docker container. Ensure the directory being mounted
 is owned by that user.
 
+### Fast Sync by Default for Named Networks
+The default sync mode for named permissionless networks, such as the Ethereum mainnet and testnets is now FAST.
+The default is unchanged for private networks.
+This default is what most users want when they are syncing but if you want to full sync, you can still do so with `--sync-mode=FULL`
+
 ## Upcoming 1.5 release 
 
 The [1.5 release](docs/1_5_Upgrade.md) is scheduled for early July. 
@@ -2134,4 +2139,4 @@ Specify `*` or `all` for `--host-whitelist` to effectively disable host protecti
  - Code style improvements (PR [#196](https://github.com/PegaSysEng/pantheon/pull/196) thanks to [@jvirtanen](https://github.com/jvirtanen))
  - Added unit tests for `Web3ClientVersion` (PR [#194](https://github.com/PegaSysEng/pantheon/pull/194) with thanks to [@jvirtanen](https://github.com/jvirtanen))
  - Removed RLPUtils from `RawBlockIterator` (PR [#179](https://github.com/PegaSysEng/pantheon/pull/179))
- - Replace the JNI based snappy library with a pure-Java version (PR [#257](https://github.com/PegaSysEng/pantheon/pull/257))
+ - Replace the JNI based snappy library with a pure-Java version (PR [#257](https://github.com/PegaSysEng/pantheon/pull/257))