docs: add configuration.md file for network/database (#104)

## Description

This adds a `configuration.md` file describing network and database
config settings.

## Related Issue

Fixes #95 

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [X] Other (security config, docs update, etc)

## Checklist before merging

- [X] Test, docs, adr added or updated as needed
- [X] [Contributor Guide
Steps](https://github.com/defenseunicorns/uds-package-sonarqube/blob/main/CONTRIBUTING.md#developer-workflow)
followed

docs/configuration.md

@@ -0,0 +1,42 @@
+# Configuration
+
+SonarQube in this package is configured through the upstream [SonarQube chart](https://github.com/SonarSource/helm-chart-sonarqube) as well as a UDS configuration chart that supports the following:
+
+## Networking
+
+Network policies are controlled via the `uds-sonarqube-config` chart in accordance with the [common patterns for networking within UDS Software Factory](https://github.com/defenseunicorns/uds-software-factory/blob/main/docs/networking.md).  SonarQube interacts with Postgresql externally and supports the following keys:
+
+- `postgres`: sets network policies for accessing a Postgres database from the SonarQube pod
+- `custom`: sets custom network policies for the SonarQube namespace - this allows for custom integrations with other services
+
+## Database
+
+SonarQube uses Postgres as its backing database service and supports the [common database providers within UDS Software Factory](https://github.com/defenseunicorns/uds-software-factory/blob/main/docs/database.md).  
+
+### Manual Database Connection
+
+If you are using the [UDS Postgres Operator](https://github.com/defenseunicorns/uds-package-postgres-operator/) or another external database that uses usernames/passwords you can use the following Helm overrides to configure it:
+
+#### `uds-sonarqube-config` chart:
+
+> [!IMPORTANT]
+> The `postgres.password` setting is not applicable when using the UDS Postgres Operator package or when supplying a secret manually!
+
+- `postgres.password` - provides a password to generate a secret to pass to SonarQube
+
+
+#### `sonarqube` chart:
+
+> [!IMPORTANT]
+> The `jdbcOverwrite.jdbcSecretName` and `jdbcOverwrite.jdbcSecretPasswordKey` settings are not applicable when providing a password to the `uds-sonarqube-config` chart manually.
+
+- `jdbcOverwrite.jdbcUsername` - provides the username to use when connecting to the database (i.e. `sonarqube.sonarqube`)
+- `jdbcOverwrite.jdbcSecretName` - provides the secret that contains the database password (defaults to `sonarqube-postgres`)
+- `jdbcOverwrite.jdbcSecretPasswordKey` - provides the secret key that contains the database password (defaults to `password`)
+- `jdbcOverwrite.jdbcUrl` - provides the endpoint, port and database name to use (i.e. `jdbc:postgresql://pg-cluster.postgres.svc.cluster.local:5432/sonarqubedb`)
+
+### IAM Roles for Service Accounts
+
+The Software Factory team has not yet tested IRSA with AWS RDS - there is an open issue linked below with further linked issues to test this that could act as a starting point to implement:
+
+https://github.com/defenseunicorns/uds-software-factory/issues/45