Add a very basic polygerrit documentation

Change-Id: I839bac852f844624d963f73fd673f1f4b5d11c02

Documentation/config-gerrit.txt

@@ -4682,6 +4682,10 @@ The contents of the `system_config` table are cached at startup
 by Gerrit.  If you modify any columns in this table, Gerrit needs
 to be restarted before it will use the new values.
 
+== Configuring the Polygerrit UI
+
+Please see link:dev-polygerrit.html[UI] on configuring the Polygerrit UI.
+
 === Configurable Parameters
 
 site_path::

Documentation/dev-polygerrit.txt

@@ -0,0 +1,37 @@
+= PolyGerrit - GUI
+
+[IMPORTANT]
+PolyGerrit is still a beta feature...
+
+Missing features in PolyGerrit:
+
+- Inline Edit
+
+- And many more features missing.
+
+== Configuring
+
+By default both GWT and PolyGerrit UI are available to users.
+
+To disable GWT but not PolyGerrit:
+----
+[gerrit]
+        enableGwtUi = false
+        enablePolyGerrit = true
+----
+
+To enable GWT but not PolyGerrit:
+----
+[gerrit]
+        enableGwtUi = true
+        enablePolyGerrit = false
+----
+
+To switch to the PolyGerrit UI you have to add `?polygerrit=1` in the URL.
+
+for example https://gerrit.example.org/?polygerrit=1
+
+To disable PolyGerrit UI, change 1 to 0, which will take you back to GWT UI.
+
+
+More information can be found in the link:https://gerrit.googlesource.com/gerrit/+/master/polygerrit-ui/[README]