Add image and streaming from USB camera

Plus a little freshen up of the readme's

oled/README.md

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+# OLED Display
+
+ROS 2 node that renders a live dashboard on the I²C OLED display.
+
+---
+
+## Dashboard contents
+
+- Robot hostname and IP address
+- Ultrasonic range reading
+- Camera pan / tilt angles
+- CPU and memory usage
+
+---
+
+## Subscribed topics
+
+| Topic | Type | Description |
+|---|---|---|
+| `/ultrasonic/range` | `sensor_msgs/Range` | Distance reading from the HC-SR04 sensor |
+| `/joint_states` | `sensor_msgs/JointState` | Current pan/tilt angles |
+
+---
+
+## Parameters
+
+| Parameter | Default | Description |
+|---|---|---|
+| `driver` | `ssd1306` | OLED driver chip: `ssd1306` or `sh1106` |
+| `i2c_port` | `1` | I²C bus number |
+| `i2c_address` | `0x3C` | I²C device address |
+| `width` | `128` | Display width in pixels |
+| `height` | `64` | Display height in pixels |
+| `rotate` | `0` | Display rotation: `0`, `1`, `2`, or `3` (0°/90°/180°/270°) |
+| `refresh_hz` | `2.0` | Display update rate |
+| `data_timeout_s` | `5.0` | Seconds before a stale reading is shown as `---` |
+
+---
+
+## Hardware
+
+The display connects over **I²C bus 1** (`/dev/i2c-1`), the same bus used by the motor controller and servo driver. Default address is `0x3C`.