Add reverse-SSHFS-based file synchronization documentation

Issue-ID: ONAPARC-551
Change-Id: Ic22d32998ad0fc29867116827679e4c4181ba596
Signed-off-by: Pawel Wieczorek <p.wieczorek2@samsung.com>
diff --git a/bootstrap/vagrant-minimal-onap/README.rst b/bootstrap/vagrant-minimal-onap/README.rst
index 2c214a9..95f2ac1 100644
--- a/bootstrap/vagrant-minimal-onap/README.rst
+++ b/bootstrap/vagrant-minimal-onap/README.rst
@@ -69,6 +69,14 @@
 .. _`v2.2.6`: https://github.com/hashicorp/vagrant/blob/v2.2.6/CHANGELOG.md#226-october-14-2019
 .. _triggers: https://www.vagrantup.com/docs/triggers/
 
+Synced Folders
+~~~~~~~~~~~~~~
+
+Environment uses reverse-SSHFS-based file synchronization for applying non-upstream changes. This
+requires installing vagrant-sshfs_ plugin and presence of `sshfs` package on the host system.
+
+.. _vagrant-sshfs: https://github.com/dustymabe/vagrant-sshfs#install-plugin
+
 
 Running
 -------