pg: create readme.md

vlib/pg/readme.md

@@ -0,0 +1,25 @@
+Before you can use this module, you must first have PostgreSQL installed on
+your system. To do this, find your OS and perform the actions listed. 
+
+**NOTE**: These instructions are meant only as a convenience. If your OS is not
+listed or you need extra help, [go here](https://www.postgresql.org/download/).
+
+### Fedora 31
+```
+sudo dnf install postgresql-server postgresql-contrib
+sudo systemctl enable postgresql # to autostart on startup
+sudo systemctl start  postgresql
+```
+
+### Debian 10/11
+```
+sudo apt-get install postgresql postgresql-client
+sudo systemctl enable postgresql # to autostart on startup
+sudo systemctl start  postgresql
+```
+
+### MacOSX (Homebrew)
+```
+brew install postgresql
+brew services start postgresql
+```