docs: note how to connect to the database

Dependencies

• [2] L4JYZ7BM doc: switch shell session code blocks to `console` type.
• [3] 3JXCTKEC Add markdown files for documentation
• [4] DWMH6NFB docs: mention foreman under hacking

Change contents

• replacement in doc/manual/src/hacking.md at line 6
  [3.6924]→[2.0:12](∅→∅)
  − ```console
  [3.6924]

  [2.12]
  + ```console
• edit in doc/manual/src/hacking.md at line 71
  [2.630]

  [2.630]
  + ```

  +

  + ## Development Tasks

  +

  + ### Connecting to the database

  +

  + Assuming you're running the the default configuration with `foreman start`,

  + open an interactive session with Postgres via:

  +

  + ```console

  + $ psql --host localhost --port 64444 hydra

  + ```

  +

  + ### Runinng the builder locally

  +

  + For `hydra-queue-runner` to successfully build locally, your

  + development user will need to be "trusted" by your Nix store.

  +

  + Add yourself to the `trusted_users` option of `/etc/nix/nix.conf`.

  +

  + On NixOS:

  +

  + ```nix

  + {

  + nix.trustedUsers = [ "YOURUSER" ];

  + }

  + ```

  +

  + Off NixOS, change `/etc/nix/nix.conf`:

  +

  + ```conf

  + trusted-users = root YOURUSERNAME