add fields back and provide better docs

README.md

@@ -60,6 +60,7 @@ The [development stack page](https://github.com/poanetwork/blockscout/wiki/Devel
   `cp apps/explorer/config/dev.secret.exs.example apps/explorer/config/dev.secret.exs`  
   `cp apps/block_scout_web/config/dev.secret.exs.example apps/block_scout_web/config/dev.secret.exs`
   <br />Linux: Update the database username and password configuration in `apps/explorer/config/dev.secret.exs`
+  <br />Mac: Remove the `username` and `password` fields from `apps/explorer/config/dev.secret.exs`  
   <br />Optional: Set up default configuration for testing.  
   `cp apps/explorer/config/test.secret.exs.example apps/explorer/config/test.secret.exs`  
   Example usage: Changing the default Postgres port from localhost:15432 if [Boxen](https://github.com/boxen/boxen) is installed.

apps/explorer/config/dev.secret.exs.example

@@ -5,8 +5,8 @@ config :explorer, Explorer.Repo,
   adapter: Ecto.Adapters.Postgres,
   database: "explorer_dev",
   hostname: "localhost",
-  #username: "postgres",
+  username: "postgres",
-  #password: "<REPLACE WITH THE PASSWORD YOU CHOSE>",
+  password: "<REPLACE WITH THE PASSWORD YOU CHOSE>",
   loggers: [],
   pool_size: 20,
   pool_timeout: 60_000,