docs: troubleshooting ideas (#272)

Co-authored-by: Juraj <36888576+jurajpiar@users.noreply.github.com>

README.md

@@ -460,6 +460,16 @@ Some tips for development:
  - for complete development environment please see https://github.com/rsksmart/rif-marketplace-dev
  - to use the CLI commands from the cloned repo use `npm run bin -- <cmd> <...args/flags>`
 
+### Troubleshooting
+
+You might have some problems during development, here are few pointers about what could be wrong.
+
+#### No events from Blockchain:
+
+ - make sure that the ABIs in Cache match contracts deployed on your network (Ganache, Testnet, etc). The same version of contracts has to be everywhere.
+ - check if confirmations are enabled (when ran in [`VERBOSE` mode](#Logging), you should see the whole Config logged). If they are, make sure you emit empty blocks to get enough confirmations.
+ - run Cache with log level [`DEBUG`](#Logging) (you can filter out database logging with log filter `-db`) and see if events are incoming to Cache
+
 ## License
 
 [MIT](./LICENSE)