fix(docs): Fix sync docs

contentful.js is doing link resolution client side if you only make an initial sync, for the second
sync it is not possible since the sdk wont have access to all the data to make such an operation.

closes #79

lib/create-contentful-api.js

@@ -178,6 +178,9 @@ export default function createContentfulApi ({
   /**
    * Synchronizes either all the content or only new content since last sync
    * See <a href="https://www.contentful.com/developers/docs/concepts/sync/">Synchronization</a> for more information.
+   * <strong> Important note: </strong> The the sync api endpoint does not support include or link resolution.
+   * However contentful.js is doing link resolution client side if you only make an initial sync.
+   * For the delta sync (using nextSyncToken) it is not possible since the sdk wont have access to all the data to make such an operation.
    * @memberof ContentfulClientAPI
    * @param  {Object} query - Query object for the sync call. One of initial or nextSyncToken always needs to be specified, but not both.
    * @param  {boolean?} query.initial - Indicates if this is the first sync. Use it if you don't have a sync token.