[chore][receiver/oracledb] Add config options to README (open-telemet…

…ry#32825)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
These options are available via the receiver's dependency on
`scraperhelper.ControllerConfig`, but weren't included in the README.

**Link to tracking Issue:** <Issue number if applicable>
[Brought up
here](open-telemetry#32741 (comment))

receiver/oracledbreceiver/README.md

@@ -54,6 +54,12 @@ receivers:
  username: otel
 ```
 
+### Optional Configuration Options
+
+- `collection_interval` (default = `10s`): The interval at which metrics should be emitted by this receiver.
+- `initial_delay` (default = `1s`): The initial time period this receiver waits before starting.
+- `timeout` (default = `0`): Timeout for each Oracle DB request. Disabled by default.
+
 ## Permissions
 
 Depending on which metrics you collect, you will need to assign those permissions to the database user: