chore: update README

Signed-off-by: Grant Linville <[email protected]>

Author: g-linville

README.md

@@ -1,2 +1,48 @@
-# gptscript-helper-sqlite
-A GPTScript credential helper for SQLite
+# gptscript-credential-sqlite
+
+This is a GPTScript [credential helper](https://docs.gptscript.ai/credentials) for SQLite. When the `sqlite` credential store
+is configured for GPTScript, it will use this helper to store credentials in a local SQLite file, located in the configuration directory.
+By default, all credentials are stored unencrypted.
+
+Only macOS and Linux are supported.
+
+## Default SQLite file location
+
+- macOS: `~/Library/Application Support/gptscript/credentials.db`
+  - if the `XDG_CONFIG_HOME` environment variable is set, the file will be located at `$XDG_CONFIG_HOME/gptscript/credentials.db`
+- Linux: `$XDG_CONFIG_HOME/gptscript/credentials.db`
+
+## Encryption Configuration
+
+To enable encryption, you need to create an encryption configuration file. We use the same type of configuration
+as [Kubernetes](https://kubernetes.io/docs/tasks/administer-cluster/encrypt-data/) does.
+
+This should allow you to use any Kubernetes-compatible KMS v2 providers, though we have not yet tested this.
+We have only tested the built-in `aesgcm` provider, which uses a key stored locally in the configuration file.
+
+### Default encryption configuration locations
+
+- macOS: `~/Library/Application Support/gptscript/encryptionconfig.yaml`
+  - if the `XDG_CONFIG_HOME` environment variable is set, the file will be located at `$XDG_CONFIG_HOME/gptscript/encryptionconfig.yaml`
+- Linux: `$XDG_CONFIG_HOME/gptscript/encryptionconfig.yaml`
+
+### Example: AES-GCM configuration with a key in the config file
+
+```yaml
+kind: EncryptionConfiguration
+apiVersion: apiserver.config.k8s.io/v1
+resources:
+  - resources:
+      # Note that the configuration here must be EXACTLY 'credentials'
+      - credentials
+    providers:
+      - aesgcm:
+          keys:
+            - name: myKey
+              secret: <key encoded in base64>
+```
+
+## Environment Variables
+
+- `GPTSCRIPT_SQLITE_FILE` - can be used to override the path to the SQLite file.
+- `GPTSCRIPT_ENCRYPTION_CONFIG_FILE` - can be used to override the path to the encryption configuration file.