add PG

documentation/PG.rst

@@ -2,5 +2,20 @@
 PG
 ############
 
-Known Issues
+The PG scenarios are collected by running simulation and record the episodes in MetaDrive simulator.
+The name PG refers to Procedural Generation, which is a technique used to generate maps.
+When a map is determined, the vehicles and objects will be spawned and actuated  according to a hand-crafted rules.
+
+Build PG Database
+===================
+
+If MetaDrive is installed, there is no any further steps required to build the database. Just run the following
+command to generate, i.e. 1000 scenarios::
+
+    python -m scenarionet.convert_pg -d /path/to/pg_database --num_scenarios 1000
+
+
+Known Issues: PG
 ==================
+
+N/A