(#3766) - add pouchdb-full-sync to external.md

docs/external.md

diff --git a/docs/external.md b/docs/external.md
index 1114bb7..7b13b91 100644
--- a/docs/external.md
+++ b/docs/external.md
@@ -40,10 +40,6 @@
 
 Implements the handy "every document is a delta" pattern, so you don't have to deal with conflicts.
 
-#### [Transform Pouch](https://github.com/nolanlawson/transform-pouch)
-
-Transforms documents before and after storage, e.g. for encryption, compression, or massaging data.
-
 #### [PouchDB Erase](https://github.com/marten-de-vries/pouchdb-erase)
 
 A replicating `db.destroy()` alternative.
@@ -52,6 +48,10 @@
 
 MongoDB-like query language, based on CouchDB 2.0. ([Live demo](http://nolanlawson.github.io/pouchdb-find/))
 
+#### [PouchDB Full Sync](https://github.com/nolanlawson/pouchdb-full-sync)
+
+Fully replicate two PouchDB/CouchDB databases, preserving absolutely all revision history.
+
 #### [PouchDB GQL](https://github.com/pouchdb/GQL)
 
 Google Query Language (GQL) queries with PouchDB. ([Documentation](http://pouchdb.com/gql.html))
@@ -104,6 +104,11 @@
 
 A plugin to let PouchDB talk streams.
 
+#### [Transform Pouch](https://github.com/nolanlawson/transform-pouch)
+
+Transforms documents before and after storage, e.g. for encryption, compression, or massaging data.
+
+
 #### [PouchDB Update](http://python-pouchdb.marten-de-vries.nl/plugins.html)
 
 A PouchDB plugin that allows you to re-use your CouchDB update functions on the client side. ([Documentation](http://pythonhosted.org/Python-PouchDB/js-plugins.html#pouchdb-update-plug-in))