better golang example readme

examples/golang/README.md

@@ -2,15 +2,27 @@
 ## Pre-requisite
 libwaku.so is needed to be compiled and present in build folder. To create it:
 
-1. Run only the first time and after changing the current commit
+- Run only the first time and after changing the current commit
 ```code
 make update
 ```
-2. Run the next every time you want to compile libwaku
+- Run the next every time you want to compile libwaku
 ```code
 make POSTGRES=1 libwaku -j4
 ```
 
+Also needed:
+
+- Install libpq (needed by Postgres client)
+  - On Linux:
+```code
+sudo apt install libpq5
+```
+  - On MacOS (not tested)
+```code
+brew install libpq
+```
+
 ## Compilation
 
 From the nwaku root folder: