Add details to postgres setup

README.md

@@ -6,7 +6,29 @@ This project was created in under a day in 2022 as a part of an assessment. It's
 To run the server, you'll need:
 * Elixir, which depends on Erlang. Detailed instructions on how to install Elixir and Erlang can be found on [the Elixir website](https://elixir-lang.org/install.html). In most cases, installing Elixir will get you a copy of Erlang as well.
 * Node.js. If you've been blessed to have never needed to download Node on your device, you can end that streak now by visiting [the Node.js download page](https://nodejs.org/en/download)
-* PostgreSQL, which you'll need running. You can find information on how to install it on [the PostgreSQL download page](https://www.postgresql.org/download/) as well. This project is set up to assume that the database username is "postgres" and the password is "postgres"
+* PostgreSQL, which you'll need running. You can find information on how to install it on [the PostgreSQL download page](https://www.postgresql.org/download/) as well.
+
+## Aside: Setting up Postgres
+By default this project assumes your PostgreSQL install has a user with the name "postgres" whose password is "postgres". Is that not the case? Either:
+
+* Change the configuration to use the right credentials. Open `./config/dev.exs` and find and edit:
+  ```elixir
+  config :bookmarker, Bookmarker.Repo,
+    username: "<YOUR USERNAME>",
+    password: "<YOUR PASSWORD>",
+  ```
+* Change your password, say, to "postgres". If you're on Linux, this would look something like:
+  ```bash
+  # Run the postgresql console as the postgres user
+  $ sudo -u postgres psql
+  # reset the password
+  postgres=# \password <username>
+  Enter new password for user "<username>":
+  Enter it again:
+  postgres=# \q
+  ```
+
+### Finally, set up and run the server
 
 ```bash
 $ cd bookmarker